[FIX] UI: add Filter\ProxyFilterField trigger on-load-code. (#11324)

Author: thibsy

components/ILIAS/UI/src/Implementation/Component/Input/Field/FilterContextRenderer.php

@@ -199,6 +199,7 @@ protected function renderProxyField(
 
         $prox = new ProxyFilterField();
         $prox = $prox->withOnClick($popover->getShowSignal());
+        $prox = $this->addTriggererOnLoadCode($prox);
         $tpl->touchBlock("tabindex");
 
         $this->bindJSandApplyId($prox, $tpl);