pg_createsubscriber: Remove obsolete comment

This comment should have been removed by commit b963913826.  There is
no replication slot check on the primary anymore.

Author: Euler Taveira <euler@eulerto.com>
Discussion: https://www.postgresql.org/message-id/697d692f-f9d3-41f6-9f0e-29a4fb18e544@app.fastmail.com

src/bin/pg_basebackup/pg_createsubscriber.c

@@ -2207,12 +2207,7 @@ main(int argc, char **argv)
 	pg_log_info("stopping the subscriber");
 	stop_standby_server(subscriber_dir);
 
-	/*
-	 * Create the required objects for each database on publisher. This step
-	 * is here mainly because if we stop the standby we cannot verify if the
-	 * primary slot is in use. We could use an extra connection for it but it
-	 * doesn't seem worth.
-	 */
+	/* Create the required objects for each database on publisher */
 	consistent_lsn = setup_publisher(dbinfo);
 
 	/* Write the required recovery parameters */