ObjectSuggestions: Don't apply base filter to $customVars query

 - The basefilter may contain relations, that are not know to `CustomvarFlat`, which can leads to errors.
    For example: RedundancygroupController:completeActions's base filter it not known to `CustomvarFlat`.

library/Icingadb/Web/Control/SearchBar/ObjectSuggestions.php

@@ -305,7 +305,7 @@ protected function queryCustomvarConfig(string $searchTerm): Select
         }
 
         $customVars->columns('flatname');
-        $this->applyBaseFilter($customVars);
+        $this->applyRestrictions($customVars);
         $customVars->filter(Filter::like('flatname', $searchTerm));
         $idColumn = $resolver->qualifyColumn('id', $resolver->getAlias($customVars->getModel()));
         $customVars = $customVars->assembleSelect();