Revert "Show empty groups with a filter chain too"

This reverts commit fadf12e98a.

modules/monitoring/library/Monitoring/Backend/Ido/Query/IdoQuery.php

@@ -633,12 +633,6 @@ abstract class IdoQuery extends DbQuery
             new Zend_Db_Expr($ours)
         ));
 
-        if (! $negate) {
-            $subQueryFilter = $subQueryFilter->orFilter(
-                new FilterExpression($ours, '', new Zend_Db_Expr('IS NULL'))
-            );
-        }
-
         $subQuery
             ->setFilter($subQueryFilter)
             ->clearGroupingRules()