Bug#32443 - trigger.test produces warnings files

Wrong syntax for mysqltest commands was used in test file.

Fixed test.

mysql-test/t/trigger.test

@@ -2250,9 +2250,9 @@ drop table table_25411_b;
 # Bug #31866: MySQL Server crashes on SHOW CREATE TRIGGER statement
 #
 
---disable-warnings
+--disable_warnings
 DROP TRIGGER IF EXISTS trg;
---enable-warnings
+--enable_warnings
 
 --error ER_TRG_DOES_NOT_EXIST
 SHOW CREATE TRIGGER trg;