[5.3] Remove unsed variable messages from enqueue messages (#42948)

* Remove unsed variable

* fix as reuested

* Add a comment

---------

Co-authored-by: Allon Moritz <allon.moritz@digital-peak.com>
Co-authored-by: Benjamin Trenkle <bembelimen@users.noreply.github.com>

libraries/src/Application/CMSApplication.php

@@ -249,10 +249,8 @@ public function enqueueMessage($msg, $type = self::MSG_INFO)
             'type'    => $inputFilter->clean(strtolower($type), 'cmd'),
         ];
 
-        // For empty queue, if messages exists in the session, enqueue them first.
-        $messages = $this->getMessageQueue();
-
-        if (!\in_array($message, $this->messageQueue)) {
+        // Get the messages of the session and add the new message if it is not already in the queue.
+        if (!\in_array($message, $this->getMessageQueue())) {
             // Enqueue the message.
             $this->messageQueue[] = $message;
         }