watch: get flags from execArgv

[efekrskl]

Fixes #61412

This seems to be a regression from cec1bd5, where watch mode switched to spawning the child using getOptionsAsFlagsFromBinding() instead of process.execArgv and the original flag ordering is not preserved.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.73%. Comparing base (9a237cd) to head (062f3a5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61779      +/-   ##
==========================================
- Coverage   89.73%   89.73%   -0.01%     
==========================================
  Files         675      675              
  Lines      204674   204674              
  Branches    39330    39327       -3     
==========================================
- Hits       183667   183665       -2     
- Misses      13283    13295      +12     
+ Partials     7724     7714      -10     

see 32 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/71315/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/71318/

[marco-ippolito]

Thanks for fixing this, LGTM