Make wait for postmaster.pid file 5 seconds as before.

This was left behind to get converted to seconds by commit
7d59d215ec065983c666b80bc2c982d13e476c48. Most likely reason for gpexpand jobs.

src/bin/pg_ctl/pg_ctl.c

@@ -672,7 +672,7 @@ test_postmaster_connection(bool do_checkpoint)
 		 * file there but it appears stale, issue a suitable warning and give
 		 * up waiting.
 		 */
-		if (i >= 5)
+		if (i >= 5 * WAITS_PER_SEC)
 		{
 			struct stat statbuf;