Display Author name/email instead of Committer name/email in git
popover.

Closes https://github.com/zed-industries/zed/issues/27625

Prior to v0.173.x, Zed displayed Author name. Regression introduced in:
- https://github.com/zed-industries/zed/pull/24593

Release Notes:

- git: Switch to displaying Git author instead of Git committer in Git
Blame popover.