message: Remove unused CIDER setting watcher
  This setting watcher for CIDER seems unused and logs a warning at the moment, so
  this change removes it.
diff: @@ -460,8 +460,6 @@ export default createReactClass({
  // (We could use isMounted, but facebook have deprecated that.)
  this.unmounted = true;
  - SettingsStore.unwatchSetting(this._ciderWatcherRef);
  -
  // update the scroll map before we get unmounted
  if (this.state.roomId) {
  RoomScrollStateStore.setScrollState(this.state.roomId, this._getScrollState());
  