Hide "abraham landed Dxyz irresponsibly" stories from feed

Summary:
Ref T13099. Ref T12787. See PHI417. Differential has new "irresponsible" warnings in the timeline somewhat recently, but these publish feed stories that don't link to the revision or have other relevant details, so they're confusing on the balance.

These have a high strength so they render on top, but we actually just want to hide them from the feed and let "abraham closed Dxyz by committing rXzzz." be the primary story.

Modularize things more so that we can get this behavior. Also, respect shouldHideForFeed() at display time, not just publishing time.

Test Plan: Used bin/differential attach-commit on a non-accepted revision to "irresponsibly land" a revision. Verified that feed story now shows "closed by commit" instead of "closed irresponsibly".

Maniphest Tasks: T13099, T12787

Differential Revision: https://secure.phabricator.com/D19179