pg-upgrade-logical: Wait until the Patroni cluster is stopped

This is a minor improvement to MR !464 (merged)

Key Changes:

Added a task to wait until the Patroni cluster is stopped. This ensures that there are no records of an active Patroni cluster in the DCS before removing the cluster from the DCS.

While the risk of encountering this issue is minimal during the upgrade of larger databases (as they take longer than 30 seconds to upgrade), we are implementing this task to further bolster reliability and prevent potential errors.

Fixed: