git_ui: horizontal is not vertical (#25961)

Fixes an issue where I was missing some brain cells and changed the git
panel's `render_entries` to a `v_flex` instead of an `h_flex`.

But actually, fixes the git panel entries from disappearing when a
scrollbar is rendered.

**Before**

![CleanShot 2025-03-03 at 16 36
52@2x](https://github.com/user-attachments/assets/9dca7b9c-318d-4b3f-ab3e-e7242fa7f73a)

**After**

![CleanShot 2025-03-03 at 16 35
59@2x](https://github.com/user-attachments/assets/c1fe5fb1-ad57-4bca-ace4-365e70a74066)


Closes #25955

Release Notes:

- Git Beta: Fixed an issue where when the git panel would need to scroll
all the items are pushed off the screen.