MDEV-13549 Fix and re-enable MTR test galera.mysql-wsrep#90

Test was missing DEBUG_SYNC cleanup `SET DEBUG_SYNC ='RESET'`.

mysql-test/suite/galera/disabled.def

@@ -17,7 +17,6 @@ galera_binlog_rows_query_log_events: MariaDB does not support binlog_rows_query_
 GAL-419 : MDEV-13549 Galera test failures
 galera_toi_ddl_fk_insert : MDEV-13549 Galera test failures
 galera_var_notify_cmd : MDEV-13549 Galera test failures
-mysql-wsrep#90 : MDEV-13549 Galera test failures
 galera_as_master_gtid : Requires MySQL GTID
 galera_as_master_gtid_change_master : Requires MySQL GTID
 galera_as_slave_replication_bundle : MDEV-13549 Galera test failures

mysql-test/suite/galera/r/mysql-wsrep#90.result

@@ -12,6 +12,7 @@ SELECT COUNT(*) = 2 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't1';
 COUNT(*) = 2
 1
 DROP TABLE t1;
+SET DEBUG_SYNC = 'RESET';
 CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) Engine=InnoDB;
 SET GLOBAL wsrep_OSU_method = "TOI";
 SET DEBUG_SYNC = 'alter_table_before_open_tables WAIT_FOR continue';
@@ -29,3 +30,4 @@ COUNT(*) = 2
 INSERT INTO t1 VALUES (3,4);
 DROP TABLE t1;
 SET GLOBAL WSREP_OSU_METHOD = TOI;
+SET DEBUG_SYNC = 'RESET';

mysql-test/suite/galera/t/mysql-wsrep#90.test

@@ -31,6 +31,7 @@ SELECT COUNT(*) = 2 FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 't1';
 
 --connection node_1
 DROP TABLE t1;
+SET DEBUG_SYNC = 'RESET';
 
 
 CREATE TABLE t1 (f1 INTEGER PRIMARY KEY) Engine=InnoDB;
@@ -63,3 +64,4 @@ INSERT INTO t1 VALUES (3,4);
 DROP TABLE t1;
 
 SET GLOBAL WSREP_OSU_METHOD = TOI;
+SET DEBUG_SYNC = 'RESET';