MDEV-6169 main.myisam-metadata fails mtr internal check

The test didn't clean debug_sync

mysql-test/r/myisam-metadata.result

@@ -13,3 +13,4 @@ SHOW TABLE STATUS LIKE 't1';
 Name	Engine	Version	Row_format	Rows	Avg_row_length	Data_length	Max_data_length	Index_length	Data_free	Auto_increment	Create_time	Update_time	Check_time	Collation	Checksum	Create_options	Comment
 t1	MyISAM	10	Dynamic	100000	27	#	#	#	0	NULL	#	#	#	latin1_swedish_ci	NULL		
 DROP TABLE t1;
+set debug_sync='reset';

mysql-test/t/myisam-metadata.test

@@ -51,3 +51,4 @@ SHOW TABLE STATUS LIKE 't1';
 --connection default
 --disconnect con1
 DROP TABLE t1;
+set debug_sync='reset';