Request GTID replication in tests that require it

Added the required calls to request GTID replication in the mysqlmon
failover tests.

maxscale-system-test/mysqlmon_rejoin_bad.cpp

@@ -22,6 +22,7 @@ int main(int argc, char** argv)
 {
     char result_tmp[bufsize];
     interactive = strcmp(argv[argc - 1], "interactive") == 0;
+    Mariadb_nodes::require_gtid(true);
     TestConnections test(argc, argv);
     MYSQL* maxconn = test.maxscales->open_rwsplit_connection(0);