test_runner: add classname hierarchy for JUnit reporter

[mag123c]

Fixes: #59417

Implements classname hierarchy for the JUnit XML reporter.
Previously, all tests had classname="test".
Now the classname reflects the suite hierarchy (e.g., classname="Math.Addition" for nested suites).

[nodejs-github-bot]

Review requested:

• @nodejs/test_runner

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.71%. Comparing base (2593291) to head (e245584).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #60220   +/-   ##
=======================================
  Coverage   89.71%   89.71%           
=======================================
  Files         695      695           
  Lines      214441   214455   +14     
  Branches    41056    41065    +9     
=======================================
+ Hits       192376   192402   +26     
+ Misses      14113    14108    -5     
+ Partials     7952     7945    -7     

Files with missing lines	Coverage Δ
lib/internal/test_runner/test.js	96.96% <100.00%> (+0.02%)	⬆️
lib/internal/test_runner/tests_stream.js	87.97% <100.00%> (+0.13%)	⬆️

... and 30 files with indirect coverage changes

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[CuriousStork]

Hello @MoLow @pmarchini

Could you take a look? Thank you.

[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70930/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/71009/

[CuriousStork]

Hello @MoLow

Could you take a look? Thank you.

[MoLow]

@mag123c, please avoid pushing new commits if unnececary as it requires an entire CI cycle every time

[github-actions]

Failed to start CI

- Validating Jenkins credentials
✔  Jenkins credentials valid
- Querying data for job/node-test-pull-request/71009/
[SyntaxError: Unexpected token '<', ..."    
  https://github.com/nodejs/node/actions/runs/24002251583

[github-actions]

Failed to start CI

- Validating Jenkins credentials
✔  Jenkins credentials valid
- Querying data for job/node-test-pull-request/71009/
[SyntaxError: Unexpected token '<', ..."    
  https://github.com/nodejs/node/actions/runs/24002689464