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

For the two ALTER TABLE statements that are interrupted by killing the
server, manually remove the #sql*.frm files, because server startup
will not remove the files.

mysql-test/suite/innodb/t/instant_alter_crash.test

@@ -120,4 +120,7 @@ SHOW CREATE TABLE t1;
 SHOW CREATE TABLE t2;
 DROP TABLE t1,t2;
 
+--remove_files_wildcard $MYSQLD_DATADIR/test #sql*.frm
+--list_files $MYSQLD_DATADIR/test
+
 SET GLOBAL innodb_purge_rseg_truncate_frequency=@saved_frequency;