Applies the same fix as #43277 to Zed's native agent, which indeed fixes
this issue for me locally (which I could only reproduce when
specifically telling the agent to not use `--no-pager`, FWIW).

Closes #42943

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- Fixed hang when the Zed Agent runs a `git` command with a pager
configured.

---------

Co-authored-by: MrSubidubi <finn@zed.dev>