Revert "fix(hangup): destroy local tracks on conference leave (#2502)"

This reverts commit 88325aeef2.
Turns out a conference with a password triggers a failed conference
join. It's going to be tricky to decipher when to do actual
cleanup, and where to shove that code, so reverting is easier for
now.

modules/UI/UI.js

 };
 
 /**
- * Invokes cleanup of large video so it stops running polling tasks and stops
- * displaying.
+ * Invokes cleanup of any deferred execution within relevant UI modules.
  *
  * @returns {void}
  */
-UI.resetLargeVideo = () => {
+UI.stopDaemons = () => {
     VideoLayout.resetLargeVideo();
 };
 

modules/UI/videolayout/LargeVideoManager.js

             this._onVideoResolutionUpdate);
 
         this.removePresenceLabel();
-
-        this.$container.remove();
     }
 
     /**

react/features/base/conference/middleware.js

 } from '../participants';
 import { MiddlewareRegistry } from '../redux';
 import UIEvents from '../../../../service/UI/UIEvents';
-import { TRACK_ADDED, TRACK_REMOVED, destroyLocalTracks } from '../tracks';
+import { TRACK_ADDED, TRACK_REMOVED } from '../tracks';
 
 import {
     createConference,
         dispatch(setAudioOnly(true));
     }
 
-    if (typeof APP === 'object') {
-        dispatch(destroyLocalTracks());
-        APP.UI.resetLargeVideo();
-    }
-
     return result;
 }
 

react/features/conference/components/Conference.web.js

      * @inheritdoc
      */
     componentWillUnmount() {
+        APP.UI.stopDaemons();
         APP.UI.unregisterListeners();
         APP.UI.unbindEvents();