Disable non-FLOSS Wikia mobile apps

No action on Wikia's end since July.
<https://translatewiki.net/wiki/Thread:Support/Closed_source_software_on_TWN%3F>

Change-Id: Ia7f32986e3b070ddbe9ec4003126e545ed6a42f1
Merge "Disable non-FLOSS Wikia mobile apps"