Fix Conpherence NUX showing empty Joinable Rooms
Summary: I moved this to setContent with the new search result layout, but failed to update NUX here.
Test Plan: Leave all rooms, get Joinable Rooms with list of 10 rooms.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Differential Revision: https://secure.phabricator.com/D16743