MDEV-36425 fix test results

followup for ce8a74f

Author: vuvova

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

@@ -17,7 +17,7 @@ connect foo_node_2,127.0.0.1,foo,,test,$port_2,;
 # Connect with foo_node_2
 connection foo_node_2;
 INSERT INTO t1 VALUES (2);
-ERROR HY000: The MariaDB server is running with the --read-only option so it cannot execute this statement
+ERROR HY000: The MariaDB server is running with the --read-only=ON option so it cannot execute this statement
 CREATE TEMPORARY TABLE t2(id int not null primary key) engine=innodb;
 INSERT INTO t2 values (1);
 DROP TABLE t2;