monitoring/CSS: Add listing-table to the hostgroup overview

refs #5543

modules/monitoring/application/views/scripts/list/hostgroups.phtml

@@ -15,7 +15,7 @@ if (! $this->compact): ?>
     <p><?= $this->translate('No host groups found matching the filter.') ?></p>
     </div>
 <?php return; endif ?>
-<table class="groupview action" data-base-target="_next">
+<table class="groupview action listing-table" data-base-target="_next">
     <thead>
         <tr>
             <th><?= $this->translate('Host Group') ?></th>