Super small update changing two instances where
`DiagnosticSeverity::HINT` was set to use the color for "info".

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)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #45637

Release Notes:

- Fixed various instances of hint level diagnostics using the color
designated for info