fs: prevent spurious recursive watch events on prefix siblings

[marcopiraccini]

Fix a bug in the JS-based recursive fs.watch (used on Linux) where deleting an entry caused spurious rename events to be emitted for unrelated sibling entries whose names share a prefix with the deleted entry.

FSWatcher#unwatchFiles(file) in lib/internal/fs/recursive_watch.js used StringPrototypeStartsWith(filename, file) to find the watched entries to remove. This match is a raw string prefix, so deleting foo also unwatched foo_, foo_bar, foo_bar/file.txt, and so on. The next time #watchFolder walked the parent directory, those still-on-disk siblings were missing from #files and were treated as newly created, firing extra rename events and re-attaching watchers redundantly.

Fix

Match by exact path, or by deletedPath + path.sep prefix, so only the deleted entry and its actual descendants are unwatched.

Fixes: #58868

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.33%. Comparing base (837910d) to head (430d3a4).
⚠️ Report is 86 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #63095    +/-   ##
========================================
  Coverage   90.33%   90.33%            
========================================
  Files         730      730            
  Lines      234205   234365   +160     
  Branches    43927    43927            
========================================
+ Hits       211559   211714   +155     
+ Misses      14370    14368     -2     
- Partials     8276     8283     +7     

Files with missing lines	Coverage Δ
lib/internal/fs/recursive_watch.js	87.11% <100.00%> (+1.84%)	⬆️

... and 44 files with indirect coverage changes

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[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73546/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73663/

[mcollina]

lgtm