MDEV-25481 Memory leak in Cached_item_str::Cached_item_str WITH TIES involving a blob

Make sure to call cached item's destructors.

mysql-test/main/fetch_first.result

@@ -1368,3 +1368,13 @@ f
 1
 1
 drop table t1;
+#
+# MDEV-25481: Memory leak upon query WITH TIES involving a blob
+#
+CREATE TABLE t (a TEXT);
+INSERT INTO t VALUES ('foo'),('bar');
+SELECT a FROM t ORDER BY a FETCH FIRST 2 ROWS WITH TIES;
+a
+bar
+foo
+DROP TABLE t;

mysql-test/main/fetch_first.test

@@ -1046,3 +1046,13 @@ SELECT SQL_BUFFER_RESULT 1 AS f FROM t1 ORDER BY f FETCH NEXT 2 ROW WITH TIES;
 SELECT 1 AS f FROM t1 ORDER BY f FETCH NEXT 2 ROW WITH TIES;
 
 drop table t1;
+
+--echo #
+--echo # MDEV-25481: Memory leak upon query WITH TIES involving a blob
+--echo #
+CREATE TABLE t (a TEXT);
+INSERT INTO t VALUES ('foo'),('bar');
+SELECT a FROM t ORDER BY a FETCH FIRST 2 ROWS WITH TIES;
+
+# Cleanup
+DROP TABLE t;

sql/sql_select.cc

@@ -14231,6 +14231,7 @@ void JOIN::cleanup(bool full)
 
     // Run Cached_item DTORs!
     group_fields.delete_elements();
+    order_fields.delete_elements();
 
     /*
       We can't call delete_elements() on copy_funcs as this will cause