Implement patch release status metric

What does this MR do and why?

Implements patch release status metric, very similar to the monthly release status metric, implemented in gitlab-com/gl-infra&1245 (closed)

Labels:

• release_date
  • This can be manually set via rake task metrics:patch_release:open. This rake task is for the release managers to manually start, when they need to modify the release date.
    • Corresponding bot comment has been edited to include a pipeline template
• versions
  • These versions are space-separated in this label. Couldn't make the versions comma-space separated because prometheus doesn't seem to like it when it has labels with commas.

Value = current release status:

• Open: created when the last patch release is being finalized for the upcoming patch version
• Warning: signals that the merging date for patch release is getting closer. Created similarly to the "announced" state for the monthly release status metric (during the initial preparation day).
  • Since the patch release task issue only gets created 2 days prior to the anticipated release day, we cannot ask the release manager to manually create this pipeline, like we do for the monthly release.
  • We'll have a followup task to create a pipeline schedule to invoke metrics:patch_release:warning rake task every Friday
  • PatchReleaseStatus class will only create the metric with the warning status if the release date is next week.
• Closed: created/updated when the default branch security MRs are merged.

Related: gitlab-com/gl-infra/delivery#20087 (closed)