Fix flaky terminal kill test (#52370)

## Context

This test was bugging me, so I had claude take a look at it.


## Self-Review Checklist

<!-- Check before requesting review: -->
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A
0512b72106Mikayla Maki committed on 3/25/2026, 3:33:56 PM· committed by GitHubparenta48bcf2
1 file changedLine totals unavailable