Don't load the apex theme for oojs-ui if we're using Minerva skin

Change-Id: I12c9f91276d34e56d0e9f5bb2e990a72756dd6b9
Dependency: Ib9d52327425f8a12e12d82f1421f5cab0774c510
Merge "Don't load the apex theme for oojs-ui if we're using Minerva skin"