FIX: ensures side panel is closed (#24822)

When navigating to /chat/threads we were not closing the side panel. It would not show as the route doesn't support it, but after if we would open a channel from the sidebar it would open the channel with an empty opened sidepanel .

plugins/chat/assets/javascripts/discourse/routes/chat-threads.js

@@ -3,8 +3,10 @@ import DiscourseRoute from "discourse/routes/discourse";
 
 export default class ChatChannelThreads extends DiscourseRoute {
   @service chat;
+  @service chatStateManager;
 
   activate() {
     this.chat.activeChannel = null;
+    this.chatStateManager.closeSidePanel();
   }
 }