Replace weird, redundant list of branches in Diffusion "Manage" UI with a link to the main branch list

Summary:
Fixes T13312. Currently, Manage → Branches has a list of branches on the same page. This has a few minor issues:

• Pager is at the top (see T13312), which is weird.
• "Default" icon is mystery meat.
• Table is kind of pointless/redundant in general?

Previously, this table had more information about technical status of each branch (autoclose/track/publish) but most of these details have been simplified/eliminated, and the main "Branches" view now has more information than it did before.

Get rid of this and just link to the main view.

Test Plan: Viewed "Branches" in UI, saw a link to the main view instead of a weird table.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13312

Differential Revision: https://secure.phabricator.com/D20584