Fix "Manage herald rules" link by removing it

Summary: Fixes T4001. I broke this some time ago and no one has complained. I don't think it gets much use, and we haven't added it for the newer apps. Just get rid of it rather than adapt the URIs for ApplicationSearch.

Test Plan: Unit tests, sent myself some email.

Reviewers: zeeg, btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4001

Differential Revision: https://secure.phabricator.com/D7355