fix(ceilometer): tweak event_update processing

Do not use the instance_type_id field as that seems to unreliably
represent the flavor_id. From what I have observed, some messages come
through as a numerical value (the idx of the flavor in the flavors
table), and some messages come through with the uuid of the flavor.

Also, remove some attributes that should not be changing after a VM is
built. This should make ops slightly more performant, and somewhat
protect a few dates we don't want changed during an update event,
deferring their modification to related create/update events.

base-helm-configs/ceilometer/ceilometer-helm-overrides.yaml

@@ -894,7 +894,7 @@ conf:
           display_name: display_name
           host: host
           availability_zone: availability_zone
-          flavor_id: instance_type_id
+          flavor_id: flavor_id
           flavor_name: instance_type
           user_id: user_id
           project_id: project_id
@@ -903,54 +903,42 @@ conf:
           instance_disk: '{"=": {"instance_id": "%s"}}'
 
       - resource_type: instance
-        metrics:
-          memory:
-          memory.usage:
-          memory.resident:
-          memory.swap.in:
-          memory.swap.out:
-          memory.bandwidth.total:
-          memory.bandwidth.local:
-          vcpus:
-          cpu:
-            archive_policy_name: ceilometer-low-rate
-          cpu_l3_cache:
-          disk.root.size:
-          disk.ephemeral.size:
-          disk.latency:
-          disk.iops:
-          disk.capacity:
-          disk.allocation:
-          disk.usage:
-          compute.instance.booting.time:
-          perf.cpu.cycles:
-          perf.instructions:
-          perf.cache.references:
-          perf.cache.misses:
+        metrics: null
         attributes:
-          host: resource_metadata.(instance_host|host)
           image_ref: resource_metadata.image_ref
-          launched_at: resource_metadata.launched_at
-          created_at: resource_metadata.created_at
-          deleted_at: resource_metadata.deleted_at
           display_name: resource_metadata.display_name
           flavor_id: resource_metadata.(instance_flavor_id|(flavor.id)|flavor_id)
           flavor_name: resource_metadata.(instance_type|(flavor.name)|flavor_name)
           server_group: resource_metadata.user_metadata.server_group
         event_update:
           - compute.instance.update
+        event_attributes:
+          id: instance_id
+          display_name: display_name
+          flavor_id: flavor_id
+          flavor_name: instance_type
+          image_ref: image_ref
+
+      - resource_type: instance
+        metrics: null
+        attributes:
+          host: resource_metadata.(instance_host|host)
+          image_ref: resource_metadata.image_ref
+          display_name: resource_metadata.display_name
+          flavor_id: resource_metadata.(instance_flavor_id|(flavor.id)|flavor_id)
+          flavor_name: resource_metadata.(instance_type|(flavor.name)|flavor_name)
+          server_group: resource_metadata.user_metadata.server_group
+        event_update:
           - compute.instance.exists
           - compute.instance.resize_confirm.end
           - compute.instance.resize_revert.end
         event_attributes:
           id: instance_id
           display_name: display_name
           host: host
-          availability_zone: availability_zone
-          flavor_id: instance_type_id
+          flavor_id: flavor_id
           flavor_name: instance_type
-          user_id: user_id
-          project_id: project_id
+          image_ref: image_ref
 
       - resource_type: instance_network_interface
         metrics: