MDEV-7353: rpl_mdev6386 fails sporadically in buildbot

Use include/sync_with_master_gtid.inc instead of --sync_with_master to avoid a
race in the test case.

In parallel replication, the old-style slave position (which is used by
--sync_with_master) is updated out-of-order between parallel threads. This
makes it possible for the position to be updated past DROP TEMPORARY TABLE t2
just before the commit of INSERT INTO t1 SELECT * FROM t2 becomes visible.

In this case, there is a small window where a SELECT just after
--sync_with_master may not see the changes from the INSERT.

mysql-test/suite/rpl/r/rpl_mdev6386.result

@@ -22,6 +22,7 @@ INSERT INTO t2 VALUE (4, 1);
 INSERT INTO t2 VALUE (5, 1);
 INSERT INTO t1 SELECT * FROM t2;
 DROP TEMPORARY TABLE t2;
+include/save_master_gtid.inc
 Contents on master:
 SELECT * FROM t1 ORDER BY a;
 a	b
@@ -41,6 +42,7 @@ SET sql_log_bin= 0;
 DELETE FROM t1 WHERE a=1;
 SET sql_log_bin= 1;
 include/start_slave.inc
+include/sync_with_master_gtid.inc
 Contents on slave after:
 SELECT * FROM t1 ORDER BY a;
 a	b

mysql-test/suite/rpl/t/rpl_mdev6386.test

@@ -31,7 +31,7 @@ INSERT INTO t2 VALUE (4, 1);
 INSERT INTO t2 VALUE (5, 1);
 INSERT INTO t1 SELECT * FROM t2;
 DROP TEMPORARY TABLE t2;
---save_master_pos
+--source include/save_master_gtid.inc
 --echo Contents on master:
 SELECT * FROM t1 ORDER BY a;
 
@@ -56,7 +56,7 @@ DELETE FROM t1 WHERE a=1;
 SET sql_log_bin= 1;
 
 --source include/start_slave.inc
---sync_with_master
+--source include/sync_with_master_gtid.inc
 --echo Contents on slave after:
 SELECT * FROM t1 ORDER BY a;