Consolidate generation of various server control commands

This is needed for better switchover control, so we can instruct
the remote repmgr to issue the appropriate server command rather
than trying to work out what it should be from the local node.

dbutils.c

@@ -3795,3 +3795,4 @@ unset_bdr_failover_handler(PGconn *conn)
 	PQclear(res);
 	return;
 }
+