Move wgMFThumbnailSizes to js hooks as its used outside Minerva

Bug: 72313
Change-Id: I32a37bb88684ee3826109f4e116f055f8752df11
WikiGrok B shouldn't depend on user having an occupation.

WikiGrok B currently doesn't show if a user has no occupation, but
they might have a nationality or something else. Let's fix that.

Change-Id: Ided08a1eea51bf8399b406fee72942b6c1c950bf
Merge "Move wgMFThumbnailSizes to js hooks as its used outside Minerva"