Add task to drop replication from secondary sites before proceeding with recovery

What does this MR do?

Adds task to remove all replication slots when recovering a demoted Primary as a new Secondary.

Secondary sites do not need replication slots. The recovery playbook also changes the setting max_replication_slots to 0, causing a conflict and preventing PostgreSQL from starting if there are leftover replication slots on the Secondary site.

Related issues

Author's checklist

When ready for review, the Author applies the workflowready for review label and mention @gitlab-org/software-delivery/get-maintainers:

• Merge request:
  • Corresponding Issue raised and reviewed by the GET maintainers team.
  • Merge Request Title and Description are up-to-date, accurate, and descriptive
  • MR targeting the appropriate branch
  • MR has a green pipeline
  • MR has no new security alerts in the widget from the Secret Detection and IaC Scan (SAST) jobs.
• Code:
  • Check the area changed works as expected across all expected permutations.
  • Check that the changes work across upgrades.
  • Documentation created/updated in the same MR if applicable