src: unlink compile cache temp file on persist failure

[lazerg]

When persisting the compile cache fails after the temporary file is created, on write, close, or rename failure, CompileCacheHandler::Persist() moves on without closing the descriptor or removing the temporary file. Under an EDQUOT/ENOSPC/EFBIG condition this leaves zero-byte temp files (and open descriptors) behind for every failed write. This adds a scope guard that closes the descriptor if still open and unlinks the temporary file unless the rename succeeded.

Fixes #65473

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.11%. Comparing base (5fc9f1f) to head (11b60ed).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #65476      +/-   ##
==========================================
- Coverage   90.13%   90.11%   -0.03%     
==========================================
  Files         751      751              
  Lines      252409   252435      +26     
  Branches    47478    47471       -7     
==========================================
- Hits       227507   227473      -34     
- Misses      16208    16263      +55     
- Partials     8694     8699       +5     

Files with missing lines	Coverage Δ
src/compile_cache.cc	81.44% <100.00%> (+1.69%)	⬆️

... and 34 files with indirect coverage changes

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