MDEV-15012: ASAN: numerous test failures in PS

First roll back changes, then free Items which can lead to memory freeing.

sql/sql_prepare.cc

@@ -3230,9 +3230,9 @@ void Prepared_statement::cleanup_stmt()
   DBUG_ENTER("Prepared_statement::cleanup_stmt");
   DBUG_PRINT("enter",("stmt: 0x%lx", (long) this));
 
+  thd->rollback_item_tree_changes();
   cleanup_items(free_list);
   thd->cleanup_after_query();
-  thd->rollback_item_tree_changes();
 
   DBUG_VOID_RETURN;
 }