R1:775d141fe6bf

Audit Feed: less verbose when the author is the committer

Summary:
If the author and the committer are the same person, do not show them twice.

From:

UsernameFoo committed <commit hash>: <commit msg> (authored by UsernameFoo).

To:

UsernameFoo committed <commit hash>: <commit msg>

This only affects the feed.

| Before | After |
|-----------|-----------|
| {F342758} | {F342764} |

Closes T15528

Test Plan: Do some mixed commits and visit /feed/query/all/. No nuclear implosions.

Reviewers…