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.

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

@@ -87,6 +87,7 @@ class Conference extends Component<Props> {
      * @inheritdoc
      */
     componentWillUnmount() {
+        APP.UI.stopDaemons();
         APP.UI.unregisterListeners();
         APP.UI.unbindEvents();