test: allow `tmpDir.path` to be modified

[avivkeller]

The behavior was changed in 8e872999c446617ce2cd429aa230203d57082937, which broke make test-npm, as it tries modifying the path used for tmpDir.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.14%. Comparing base (f75a126) to head (2e2ad90). Report is 64 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #58173      +/-   ##
==========================================
- Coverage   90.17%   90.14%   -0.03%     
==========================================
  Files         630      630              
  Lines      186756   186756              
  Branches    36664    36648      -16     
==========================================
- Hits       168399   168359      -40     
- Misses      11179    11183       +4     
- Partials     7178     7214      +36     

see 29 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/66624/

[avivkeller]

This PR is author ready, no?

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/66718/

[avivkeller]

It's been seven days, can this land?

[nodejs-github-bot]

Landed in 563be01292a84bc244a6e725b10b151bb7b7fab0