Issue #2578539 by longwave: Remove obsolete forum_update_last_removed()

core/modules/forum/forum.install

@@ -175,10 +175,3 @@ function forum_schema() {
 
   return $schema;
 }
-
-/**
- * Implements hook_update_last_removed().
- */
-function forum_update_last_removed() {
-  return 7003;
-}