Trigger release environment deployment when stable branch is created

Context

At the moment, a new release-environment is created at the point of the first MR merged to the stable branch. It is designed this way because prior to that, we consider the same code was already deployed and tested by GitLab.com, Pre instance and Release instance.

Problem Statements

During #21264 (closed), there was a situation that a QA failure with 18.1 was detected first by a release-environment deployment. Since the deployment rans at the beginning of the patch release process, it required the release managers to work with DevEx to debug and roll out a fix in a short time period. Thus, if the release environment deployment happened earlier, like when the stable branch was created, we would catch the issue earlier and there would be more time to handle the situation.

Questions

• If release-environment deployment runs when the stable branch pipeline is created - which is during the monthly release, does a failed branch pipeline block any release steps?
• Do we need to add a guidance for the release managers to continue the monthly release process even if a release environment deploy fails, and comeback to fix it later?

Exit Criteria

• Trigger start-release-environments when initial RC is tagged and the stable branch is created.