minor #17730 [Mailer] remove QueuingMessageEvent (MrYamous)

This PR was merged into the 6.2 branch.

Discussion
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[Mailer] remove `QueuingMessageEvent`

Related to [47992 in code](symfony/symfony#47992) - QueuingMessageEvent class has been removed due to BC break

Related to #17111 in doc

Remove explanations about this specific event but keep new methods added in previously existing MessageEvent

Commits
-------

9bc26d1 remove QueuingMessageEvent from documentation

Author: javiereguiluz

mailer.rst

@@ -1480,9 +1480,16 @@ the email is sent::
         if (!$message instanceof Email) {
             return;
         }
-        // do something with the message
+        // do something with the message (logging, ...)
+
+        // and/or add some Messenger stamps
+        $event->addStamp(new SomeMessengerStamp());
     }
 
+.. versionadded:: 6.2
+
+    Methods ``addStamp()`` and ``getStamps()`` were introduced in Symfony 6.2.
+
 .. tip::
 
     When using a ``MessageEvent`` listener to
@@ -1497,48 +1504,6 @@ and their priorities:
 
     $ php bin/console debug:event-dispatcher "Symfony\Component\Mailer\Event\MessageEvent"
 
-QueuingMessageEvent
-~~~~~~~~~~~~~~~~~~~
-
-**Event Class**: :class:`Symfony\\Component\\Mailer\\Event\\QueuingMessageEvent`
-
-.. versionadded:: 6.2
-
-    The ``QueuingMessageEvent`` class was introduced in Symfony 6.2.
-
-``QueuingMessageEvent`` allows to add some logic before the email is sent to
-the Messenger bus (this event is not dispatched when no bus is configured); it
-extends ``MessageEvent`` to allow adding Messenger stamps to the Messenger
-message sent to the bus::
-
-    use Symfony\Component\EventDispatcher\EventSubscriberInterface;
-    use Symfony\Component\Mailer\Event\QueuingMessageEvent;
-    use Symfony\Component\Mime\Email;
-
-    public function onMessage(QueuingMessageEvent $event): void
-    {
-        $message = $event->getMessage();
-        if (!$message instanceof Email) {
-            return;
-        }
-        // do something with the message (logging, ...)
-
-        // and/or add some Messenger stamps
-        $event->addStamp(new SomeMessengerStamp());
-    }
-
-This event lets listeners do something before a message is sent to the queue
-(like adding stamps or logging) but any changes to the message or the envelope
-are discarded. To change the message or the envelope, listen to
-``MessageEvent`` instead.
-
-Execute this command to find out which listeners are registered for this event
-and their priorities:
-
-.. code-block:: terminal
-
-    $ php bin/console debug:event-dispatcher "Symfony\Component\Mailer\Event\QueuingMessageEvent"
-
 SentMessageEvent
 ~~~~~~~~~~~~~~~~