Render the list of categories as a normal subheading for logged in mobile users.

Depends on Change-Id I09679ac8515768a34c1ee436dfd32a50c9a89011 on mediawiki/core

Bug: 22660
Change-Id: I13afda7037082cc0aab98f69d37b296b18edc1aa
Merge "Render the list of categories as a normal subheading for logged in mobile users."