Update default-for-task-types for agent service in flyte charts value yaml

[Future-Outlier]

Tracking issue

#3936

Describe your changes

Values in the default-for-task-types section should begin with a hyphen (-).
Below is an example configuration that I use in my flyte-single-binary-local-dev.yaml file for Flyte development in dev mode:

tasks:
  task-plugins:
    enabled-plugins:
      - agent-service
      - container
      - sidecar
      - K8S-ARRAY
    default-for-task-types:
      - dispatcher: agent-service
      - sensor: agent-service
      - spark: agent-service
      - bigquery_query_job_task: agent-service
      - custom_task: agent-service
      - container: container
      - container_array: K8S-ARRAY

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Update

whether begins with a hyphen (-) or not, the value can be passed correctly.
So I will close this PR.