MDEV-14029 Server does not remove #sql*.frm files after crash during ALTER TABLE

Add a check for #sql* files in test and mysql subdirs to the testcase check

mysql-test/include/check-testcase.test

@@ -73,5 +73,10 @@ if (!$tmp) {
 }
 
 call mtr.check_testcase();
+
+let $datadir=`select @@datadir`;
+list_files $datadir/test #sql*;
+list_files $datadir/mysql #sql*;
+
 --enable_query_log