Draft: Introduce delivery_release_monthly_info metric

What does this MR do and why?

For issue gitlab-com/gl-infra/delivery#20023 (closed)

This MR introduces the delivery_release_monthly_info metric.

• The main use case of this metric is to update the commit sha that is to be displayed on the release dashboard.
  • This commit sha should be the latest commit on gitlab-org/gitlab that was deployed to the production environment (gprd).
• The value of this metric equates to the monthly release's current status, similarly to delivery_release_monthly_status metric (which does not contain the commit sha).
  • The status indicates at which points of the release this commit sha is to be refreshed.

This MR is closed for now to focus on _status metric for monthly and patch releases for the first iteration, but feel free to re-open or reference it when we want to implement a sha-containing metric!