FIX: correctly reset active message on destroy (#23844)

It should prevent any message action to still show after a transition while hovering a message (eg: link to channel settings from a message).

plugins/chat/assets/javascripts/discourse/components/chat-message.gjs

@@ -313,6 +313,7 @@ export default class ChatMessage extends Component {
     cancel(this._makeMessageActiveHandler);
     cancel(this._debounceDecorateCookedMessageHandler);
     this.#teardownMentionedUsers();
+    this.chat.activeMessage = null;
   }
 
   @action