Bug #42188: After-push test file update (see bug 42321)

mysql-test/t/user_var.test

@@ -292,7 +292,7 @@ drop table t1;
 CREATE TABLE t1 (i INT);
 CREATE TRIGGER t_after_insert AFTER INSERT ON t1 FOR EACH ROW SET @bug42188 = 10;
 INSERT INTO t1 VALUES (1);
---change_user
+--change_user root,,test
 INSERT INTO t1 VALUES (1);
 DROP TABLE t1;