Fix FS-related issues that were causing a test failure on linux (#13072)

This fixes `project_tests::rescan_and_remote_updates` .

That test was actually correctly failing, revealing two bugs on Linux.

Release Notes:

- Fixed an issue where file renames were not detected on Linux.
- Fixed performance problems caused by excessive file system events on
Linux.

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Co-authored-by: Mikayla <mikayla@zed.dev>