MDEV-13549 Fix and re-enable MTR test galera.galera_as_master

Was failing due to missing RESET MASTER

mysql-test/suite/galera/disabled.def

@@ -41,7 +41,6 @@ lp1376747 : MDEV-13549 Galera test failures
 galera_toi_ddl_nonconflicting : MDEV-13549 Galera test failures
 galera_parallel_simple : MDEV-13549 Galera test failures
 galera_admin : MDEV-13549 Galera test failures
-galera_as_master: MDEV-13549 Galera test failures 10.1
 galera_pc_ignore_sb : MDEV-13549 Galera test failures 10.1
 galera_lock_table : MDEV-13549 Galera test failures 10.1
 MW-284 : MDEV-13549 Galera test failures 10.1

mysql-test/suite/galera/r/galera_as_master.result

@@ -47,3 +47,4 @@ DROP TABLE t2, t3;
 STOP SLAVE;
 RESET SLAVE ALL;
 CALL mtr.add_suppression('You need to use --log-bin to make --binlog-format work');
+RESET MASTER;

mysql-test/suite/galera/t/galera_as_master.test

@@ -35,14 +35,14 @@ SELECT * FROM t3;
 SELECT * FROM t4;
 
 --connection node_3
-SHOW TABLES;
-
 --let $wait_condition = SELECT COUNT(*) = 2 FROM t1;
 --source include/wait_condition.inc
 
 --let $wait_condition = SELECT COUNT(*) = 3 FROM t4;
 --source include/wait_condition.inc
 
+SHOW TABLES;
+
 SELECT * FROM t1;
 SELECT * FROM t4;
 
@@ -63,3 +63,5 @@ RESET SLAVE ALL;
 
 CALL mtr.add_suppression('You need to use --log-bin to make --binlog-format work');
 
+--connection node_1
+RESET MASTER;