[Obs Alerting] API integration test coverage for Obs Alerting API usage

[jasonrhodes]

We need to confirm we have adequate test coverage for Observability Alerting API integration tests. I expect this means both incoming (e.g. creation of our various rule types are well tested) and outgoing (we have tests that assert against the way we interact with any ES APIs or Kibana APIs such as saved objects, etc). It's possible that the platform response ops tests already cover these cases for us and we can close this without adding our own tests, but we may want a few that test specifics of our own rule types, too. Let's discuss.

Please feel free to refine/add detail to this issue description. The A/C is to identify any missing test coverage in this area and either create the needed tests or create issues to make sure these tests are created before GA.

[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[jasonrhodes]

Closing this in favor of individual issues outlined in this meta --- #183263