git_ui: Use margin instead of padding for blame entries (#38397)

This makes the hover background change keep a visible border element
between the gutter and blame entries

Release Notes:

- N/A *or* Added/Fixed/Improved ...
d85a6db6a3Lukas Wirth committed on 9/18/2025, 8:22:26 AM· committed by GitHubparent4b1e78c
1 file changedLine totals unavailable