fix(aws_cloudwatch_logs sink): Skip healthcheck for templated group names

[iandelahorne]

Summary

If the log group name is templated, exit the healthcheck with Ok before attempting to verify that it exists. Previous behaviour tried to call describe_log_groups on a template string ({{ cloudwatch_log_group }}) which resulted in an error from the Cloudwatch service as curly braces aren't part of a valid log group name, and the healthcheck didn't handle this error.

Additionally, add a test for the healthcheck when the log group doesn't exist and create_missing_group is false.

Vector configuration

sources:
  demo_logs:
    type: demo_logs
    format: json

transforms:
  set_cloudwatch_log_group_name:
    type: remap
    inputs:
      - demo_logs
    source: |
      .cloudwatch_log_group_name = "demo-logs"

sinks:
  cloudwatch_public_actions:
    type: aws_cloudwatch_logs
    inputs:
      - set_cloudwatch_log_group_name
    region: "${AWS_REGION:-us-east-1}"
    group_name: "{{ cloudwatch_log_group_name }}"
    stream_name: "vector"
    create_missing_group: false
    encoding:
      codec: json

How did you test this PR?

Besides the unit tests, this branch with the above config produces the logs:

2026-04-06T16:24:50.352232Z  INFO vector::topology::running: Running healthchecks.
2026-04-06T16:24:50.353087Z  INFO vector::sinks::aws_cloudwatch_logs::healthcheck: Skipping healthcheck log group check: `group_name` is dynamic.

Change Type

• Bug fix
• New feature
• Dependencies
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

References

Closes: #10787

Notes

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[github-actions]

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[iandelahorne]

I have read the CLA Document and I hereby sign the CLA

[iandelahorne]

recheck