## Context

Cleanup of the one-off workflow added in #51958. Both affected PRs
(#51897, #50372) now have passing checks and correct size labels.

## How to Review

- Single file deletion: `.github/workflows/fix-size-check.yml`

## 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 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