Use modern ApplicationTransactions "no effect" stuff in Maniphest

Summary: Fixes T912. This was very nearly working, it just needed a little tweaking on the last mile.

Test Plan:
Made updates with no effect, and updates with an effect. Made a no-effect update and posted just the comment part.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T912

Differential Revision: https://secure.phabricator.com/D8543