Remove selection highlights from deleted diff editors on blur (#11772)

Follow-up of https://github.com/zed-industries/zed/pull/11710

Release Notes:

- Removed extra line highlights when deleted diff editors loose focus
fcd5fa9257Kirill Bulatov committed on 5/13/2024, 10:15:49 PM· committed by GitHubparentcb34507
2 files changedLine totals unavailable