[CI] Ensure review app cleanup runs when expected

Summary

Fixes jobs triggering before they were needed

Prevents the cleanup jobs from triggering immediately as long as the pipeline is succeeding - instead, they will only trigger when their rules match.

This was related to the needs: [] workaround.

Automatically clean up review apps in 1 hour

Automatically cleans up review apps in 1 hour instead of 4 days. Added documentation on how to pin the environment if further investigation is needed.

This will ensure that our clusters have enough breathing room to run review apps for merge requests and help us avoid stale releases.

Closes #334 (closed)

Testing

• In https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/pipelines/374808838, the cleanup jobs didn't trigger directly after the Review stage passed
• In https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/pipelines/374808838, the environments auto-uninstalled after 1 hour