monitoring: Fix table class in downtimes-header.phtml

modules/monitoring/application/views/scripts/partials/downtime/downtimes-header.phtml

@@ -2,7 +2,7 @@
 use Icinga\Module\Monitoring\Object\Host;
 use Icinga\Module\Monitoring\Object\Service;
 ?>
-<table class="action" data-base-target="_next">
+<table class="state-table common-table" data-base-target="_next">
     <tbody>
     <?php
     foreach ($this->downtimes as $i => $downtime):
@@ -37,4 +37,4 @@ use Icinga\Module\Monitoring\Object\Service;
         )
     ) ?>
 </p>
-<?php endif ?>
+<?php endif ?>