Remove gradebook in $_SESSION when cidReset is set - refs BT#12404

main/inc/local.inc.php

@@ -1017,6 +1017,10 @@ if (isset($cidReset) && $cidReset) {
         if (api_get_group_id()) {
             Session::erase('_gid');
         }
+
+        if (api_is_in_gradebook()) {
+            api_remove_in_gradebook();
+        }
     }
 } else {
     // Continue with the previous values