Remove unusual explicit calls to policy capability descriptions from Diviner

Summary: Fixes T12015. This is weird and probably got copy/pasted from something else that was also being weird, since the methods were empty and I previously removed them.

Test Plan: Edited a book in Diviner.

Reviewers: chad, avivey

Reviewed By: avivey

Maniphest Tasks: T12015

Differential Revision: https://secure.phabricator.com/D17056