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

Relates #1194

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