split wpt out of npm test

[mcollina]

Remove test:wpt from the test:javascript:no-jest script chain so that local npm test no longer runs the slow WPT tests. The test:wpt script remains available for explicit invocation.

In CI, add a separate WPT step to the test-without-intl job so WPT still always runs in CI. The reusable nodejs.yml workflow already had WPT as a separate step, so no change is needed there.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.47%. Comparing base (10d93fc) to head (b55f48b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5588      +/-   ##
==========================================
- Coverage   93.47%   93.47%   -0.01%     
==========================================
  Files         110      110              
  Lines       37665    37670       +5     
==========================================
+ Hits        35208    35212       +4     
- Misses       2457     2458       +1     

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