test: use the skipIfNoWatch() utility function

[lpinca]

Use the skipIfNoWatch() utility function in
test/parallel/test-fs-promises-watch-iterator.js.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.77%. Comparing base (c1402c6) to head (d455291).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #61531    +/-   ##
========================================
  Coverage   89.77%   89.77%            
========================================
  Files         672      672            
  Lines      203930   203809   -121     
  Branches    39207    39190    -17     
========================================
- Hits       183082   182976   -106     
+ Misses      13175    13168     -7     
+ Partials     7673     7665     -8     

see 31 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/71058/