Add restore_command to recovery.conf in patroni cluster

Adding wal-g wal-fetch as a restore_command to the recovery.conf in our patroni cluster would help with catching up from a big replication delay by loading wal files from GCS until we are close enough to switch over to streaming replication (which will be done transparently by postgres).

This would reduce the load on the primary and also enable recovering when WAL files already are missing on the primary.

We already have wal-g binaries installed on all patroni nodes in gstg and gprd. But while gstg will work out of the box, because we use wal-g for wal-push there already we need to point the wal-g configuration in gprd to the wal-e GCS bucket, as we did not enable wal-g wal-push there yet.

This is a corrective action for production#2570 (closed).