Continue reducing callers to getCallsign()

Summary: Ref T4245. More of the same, just narrowing down the easy cases.

Test Plan:

• Called diffusion.querycommit.
• Browsed branches.
• Browsed repository.
• Browsed directory.
• Searched for stuff.
• Viewed a commit.
• Viewed a file diff.
• Edited a commit.
• Viewed history.
• Viewed tags.
• Viewed push log.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4245

Differential Revision: https://secure.phabricator.com/D14929