[PG14] Automate rollback
Implement the new playbook and/or adapt the existing ones for the rollback of the pg upgrade to the major version 13.
The decision on what will be implemented will be taken in the issue: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/16384
Acceptance criteria:
-
Implement the changes or new playbooks for the rollback of the PostgreSQL upgrade