Add telemetry logging health check

[rafaelwestphal]

Description

Adding a telemetry logging endpoint healthcheck for Ops Agent.

Related issue

b/437088366

How has this been tested?

Manual tested in VMs

1. Success Case (All permissions and scopes granted)
   VM: telemetry-test-vm-logs-test

2026/04/14 17:54:18 [Ports Check] Result: PASS
2026/04/14 17:54:18 [Network Check] Result: PASS
{"level":"info","ts":1776189258.1784217,"caller":"logs/logs.go:120","msg":"[API Check] Result: PASS"}
2026/04/14 17:54:18 [API Check] Result: PASS
2026/04/14 17:54:18 Startup checks finished

2. Missing Scope Case (Missing logging.write scope)
   VM: telemetry-test-vm-no-scope-logs

2026/04/14 17:55:43 [Ports Check] Result: PASS
2026/04/14 17:55:43 [Network Check] Result: PASS
2026/04/14 17:55:43 [API Check] Result: FAIL, Error code: LogApiScopeErr, Failure: VM is missing the https://www.googleapis.com/auth/logging.write scope., Solution: Add the https://www.googleapis.com/auth/logging.write scope to the Compute Engine VM., Resource: https://cloud.google.com/stackdriver/docs/solutions/agents/ops-agent/authorization
2026/04/14 17:55:43 Startup checks finished

3. Permission Denied Case (Missing IAM permission)
   VM: telemetry-test-vm-no-perm

2026/04/14 17:57:12 [Ports Check] Result: PASS
2026/04/14 17:57:12 [Network Check] Result: PASS
2026/04/14 17:57:12 [API Check] Result: ERROR, Detail: rpc error: code = InvalidArgument desc = Request contains an invalid argument.
2026/04/14 17:57:12 Startup checks finished

(Note: The InvalidArgument error is tracked by bug b/502341191 as it should ideally be a permission error).

4. API Disabled Case (Telemetry API disabled in project)
   VM: telemetry-test-vm-logs-test

2026/04/14 18:00:55 [Ports Check] Result: PASS
2026/04/14 18:00:55 [Network Check] Result: PASS
2026/04/14 18:00:55 [API Check] Result: FAIL, Error code: TelApiDisabledErr, Failure: The Telemetry API is disabled or not accessible in the current Google Cloud project., Solution: Verify that telemetry.googleapis.com is enabled in your Google Cloud project., Resource: https://docs.cloud.google.com/stackdriver/docs/reference/api-overview
2026/04/14 18:00:55 Startup checks finished

Checklist:

• Unit tests
  • [] Unit tests do not apply.
  • Unit tests have been added/modified and passed for this PR.
• Integration tests
  • Integration tests do not apply.
  • Integration tests have been added/modified and passed for this PR.
• Documentation
  • This PR introduces no user visible changes.
  • This PR introduces user visible changes and the corresponding documentation change has been made.
• Minor version bump
  • This PR introduces no new features.
  • This PR introduces new features, and there is a separate PR to bump the minor version since the last release already.
  • This PR bumps the version.