CI: feature/backups: scale rails deployments instead of deleting pods

What does this MR do?

CI: feature/backups: scale rails deployments instead of deleting pods

Use kubectl scale to scale Rails deployments down before performing restore.

• get_hpa_minreplicas(app) fetches minReplicas from the associated HPA object.
• scale_deployment(app, replicas)
• scale_rails_down() scales to 0 replicas
• scale_rails_up() scales to minimum replicas (from HPA)

Ideally:

• Prevent DB deadlocks
• Remove 'Invalid user or password' due to locked root account
• Replicate how actual users should be restoring. https://docs.gitlab.com/charts/backup-restore/restore.html#restoring-the-backup-file

Related issues

Related to #4708 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion.

Required

• Merge Request Title and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.