Monthly release pipeline: successful deploy to release.gitlab.net verification

Context

During the monthly release process, after tagging the releases, there are manual steps for the release managers to go check that the latest patch version is successfully deployed and running on release.gitlab.net.

Monthly release issue tasks example

• Validate 16.11.0 has been deployed to the release environment

This issue is to automate the release.gitlab.net deployment verification process by implementing a job for the monthly release pipeline.

Proposal

• Use the implementation from #20289 (closed)
• This check should be in the same stage as the tag
• This check should be after the check that the CNG images are successfully built
• Send notification to release-tools with the status
• The job should be retry-able
• Follow guidelines for the release pipelines in https://gitlab.com/gitlab-org/release-tools/-/blob/master/doc/release-pipelines.md

Exit Criteria

• Release managers can rely on the the monthly release pipeline to perform this check
• An announcement gets sent to f_upcoming_release with the status of the pipeline (failed or success)
• The release task issue is updated to use the monthly release pipeline for the steps the pipeline automates