[BUG]some required values are missing in the template when getting cluster mode milvus

[tianyue86]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Get cluster mode milvus template by setting mode=cluster

helm template milclu02 ./addons-cluster/milvus --version 1.0.0-alpha.0 --set mode=cluster 
---
# Source: milvus-cluster/templates/cluster.yaml
apiVersion: apps.kubeblocks.io/v1
kind: Cluster
metadata:
  namespace: default
  name: milclu02
  labels: 
    helm.sh/chart: milvus-cluster-1.0.0-alpha.0
    app.kubernetes.io/version: "2.3.2"
    app.kubernetes.io/instance: milclu02
spec:
  clusterDef: milvus
  topology: cluster
  terminationPolicy: Delete
  componentSpecs:
    - name: proxy
      replicas: 1      
      resources:
        limits:
          cpu: "0.5"
          memory: "0.5Gi"
        requests:
          cpu: "0.5"
          memory: "0.5Gi"
      serviceRefs:        
        - name: milvus-meta-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-log-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-object-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:       
      disableExporter: true
    - name: mixcoord
      replicas: 1      
      resources:
        limits:
          cpu: "0.5"
          memory: "0.5Gi"
        requests:
          cpu: "0.5"
          memory: "0.5Gi"
      serviceRefs:        
        - name: milvus-meta-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-log-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-object-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:       
      disableExporter: true
    - name: datanode
      replicas: 1      
      disableExporter: true      
      resources:
        limits:
          cpu: "0.5"
          memory: "0.5Gi"
        requests:
          cpu: "0.5"
          memory: "0.5Gi"
      serviceRefs:        
        - name: milvus-meta-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-log-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-object-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:       
      disableExporter: true
    - name: indexnode
      replicas: 1      
      disableExporter: true      
      resources:
        limits:
          cpu: "0.5"
          memory: "0.5Gi"
        requests:
          cpu: "0.5"
          memory: "0.5Gi"
      serviceRefs:        
        - name: milvus-meta-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-log-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-object-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:       
      disableExporter: true
    - name: querynode
      replicas: 1      
      disableExporter: true      
      resources:
        limits:
          cpu: "0.5"
          memory: "0.5Gi"
        requests:
          cpu: "0.5"
          memory: "0.5Gi"
      serviceRefs:        
        - name: milvus-meta-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-log-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:         
        - name: milvus-object-storage
          namespace: 
          clusterServiceSelector:
            cluster: 
            service:
              component: 
              service: 
              port: 
            credential:
              component: 
              name: 
          serviceDescriptor:       
      disableExporter: true

2. apply this yaml to create milvus cluster
   ===> some required values are missing

tianyue@apeclouds-MacBook-Pro kubeblocks-addons % k apply -f milvuscluster.yaml
The Cluster "milclu02" is invalid: 
* spec.componentSpecs[0].serviceRefs[0].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[0].serviceRefs[0].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[0].serviceRefs[0].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[0].serviceRefs[0].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[0].serviceRefs[1].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[0].serviceRefs[1].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[0].serviceRefs[1].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[0].serviceRefs[1].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[0].serviceRefs[2].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[0].serviceRefs[2].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[0].serviceRefs[2].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[0].serviceRefs[2].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[1].serviceRefs[0].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[1].serviceRefs[0].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[1].serviceRefs[0].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[1].serviceRefs[0].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[1].serviceRefs[1].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[1].serviceRefs[1].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[1].serviceRefs[1].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[1].serviceRefs[1].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[1].serviceRefs[2].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[1].serviceRefs[2].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[1].serviceRefs[2].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[1].serviceRefs[2].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[2].serviceRefs[0].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[2].serviceRefs[0].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[2].serviceRefs[0].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[2].serviceRefs[0].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[2].serviceRefs[1].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[2].serviceRefs[1].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[2].serviceRefs[1].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[2].serviceRefs[1].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[2].serviceRefs[2].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[2].serviceRefs[2].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[2].serviceRefs[2].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[2].serviceRefs[2].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[3].serviceRefs[0].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[3].serviceRefs[0].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[3].serviceRefs[0].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[3].serviceRefs[0].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[3].serviceRefs[1].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[3].serviceRefs[1].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[3].serviceRefs[1].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[3].serviceRefs[1].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[3].serviceRefs[2].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[3].serviceRefs[2].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[3].serviceRefs[2].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[3].serviceRefs[2].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[4].serviceRefs[0].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[4].serviceRefs[0].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[4].serviceRefs[0].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[4].serviceRefs[0].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[4].serviceRefs[1].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[4].serviceRefs[1].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[4].serviceRefs[1].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[4].serviceRefs[1].clusterServiceSelector.cluster: Required value
* spec.componentSpecs[4].serviceRefs[2].clusterServiceSelector.credential.component: Required value
* spec.componentSpecs[4].serviceRefs[2].clusterServiceSelector.credential.name: Required value
* spec.componentSpecs[4].serviceRefs[2].clusterServiceSelector.service.service: Required value
* spec.componentSpecs[4].serviceRefs[2].clusterServiceSelector.cluster: Required value
* <nil>: Invalid value: "null": some validation rules were not checked because the object was invalid; correct the existing errors to complete validation

Expected behavior
A clear and concise description of what you expected to happen.

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• Version [e.g. 22]

Additional context
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[shanshanying]

pls set servicerRef when rendering the template.

make sure clusters, etcdm-cluster, pulsarm-cluster and miniom-cluster have been created.

e.g.
set valeus to

storage:
  meta:
    mode: serviceref  # optional: incluster, serviceref
    serviceRef:
      namespace: default
      cluster:
        name: etcdm-cluster
        component: etcd
        service: headless
        port: client
        credential:
      serviceDescriptor:
  log:
    mode: serviceref  # optional: incluster, serviceref
    serviceRef:
      namespace: default
      cluster:
        name: pulsarm-cluster
        component: broker
        service: headless
        port: pulsar
        credential:
      serviceDescriptor:
  object:
    mode: serviceref  # optional: incluster, serviceref
    serviceRef:
      namespace: default
      cluster:
        name: miniom-cluster
        component: minio
        service: headless
        port: http
        credential: admin
      serviceDescriptor: