WL#11974 Remove MyISAM as the engine used for on-disk internal temporary tables.

Author: Sergey Glukhov

mysql-test/include/subquery_mat.inc

@@ -1544,20 +1544,13 @@ WHERE t1.a NOT IN (
 set @save_heap_size= @@max_heap_table_size;
 set @@max_heap_table_size= 16384;
 
-# Test both disk-based engines:
-set @saved_engine=@@internal_tmp_disk_storage_engine;
-set global internal_tmp_disk_storage_engine = 'myisam';
+# Test disk-based engine:
 
 # Subq-materialization can be used and gives correct result:
 eval EXPLAIN $query;
 eval $query;
 
-set global internal_tmp_disk_storage_engine = 'innodb';
-eval EXPLAIN $query;
-eval $query;
-
 DROP TABLE t1;
-set global internal_tmp_disk_storage_engine = @saved_engine;
 set @@max_heap_table_size= @save_heap_size;
 
 --echo #

mysql-test/include/with_non_recursive.inc

@@ -804,12 +804,6 @@ with
 
 drop table sales_days;
 
---echo # Tmp table cannot be MyISAM
-set global internal_tmp_disk_storage_engine=myisam;
---error ER_SWITCH_TMP_ENGINE
-with qn as (select 1) select * from qn;
-set global internal_tmp_disk_storage_engine=default;
-
 --echo # Special parser command not allowed to users.
 --error ER_PARSE_ERROR
 parse_cte ( select 1 ) ;