MDEV-22384 Wrong estimate of affected BLOB columns in update of PRIMARY KEY

During the UPDATE of PRIMARY KEY columns, we may miscalculate the
size of the clustered index record.

row_upd_clust_rec_by_insert(): Pass the total number of off-page columns,
which may include such columns that were inherited from the record
and not created as part of the UPDATE operation.

This is based on
mysql/mysql-server@490c45e8c8e07197958dbb21214fd45ed668b559
which is a follow-up to
mysql/mysql-server@1fa475b85d24de4b9ce2958c0eed738c221fc82c
which we filed and fixed as MDEV-21511.

No test case was provided by Oracle.

storage/innobase/row/row0upd.cc

@@ -2805,8 +2805,7 @@ row_upd_clust_rec_by_insert(
 	mtr_commit(mtr);
 
 	err = row_ins_clust_index_entry(
-		index, entry, thr,
-		node->upd_ext ? node->upd_ext->n_ext : 0);
+		index, entry, thr, dtuple_get_n_ext(entry));
 	node->state = UPD_NODE_INSERT_CLUSTERED;
 
 	mem_heap_free(heap);