Closes#26847
Release Notes:
- Updated Git panel background to use panel_background instead of
ElevationIndex::Surface.bg(cx) for consistency with other panels.
- Removed redundant GitStatusColors struct from status.rs and refactored
to use existing theme colors.
- Adjusted Color enum mappings in color.rs to reference
version_control_* colors instead of status() for better alignment with
the theme system.
- Cleaned up unused or redundant code.