Remove field selector on Diff view and Revision List View

Summary:
Ref T2222. This has some minor functionality regressions:

• The plain diff page no longer shows unit/test status. I want to give diffs separate custom fields for this.
• It was technically possible to shove more data on the list view, although this doensn't affect the default config.

Test Plan: Looked at list view, diff detail view. Grepped for changes.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2222

Differential Revision: https://secure.phabricator.com/D8470