path: skip resolve normalize for clean absolute paths

[anonrig]

posix.resolve always runs normalizeString, even when the merged path has no . / .. segments and no empty // segments. Skip that pass and drop the trailing slash the join added. When process.cwd() fails, the relative path still goes through normalizeString so path.resolve() stays ..

Official benchmark/path/relative-posix.js (--no-node-snapshot, 5 alternating runs vs parent):

paths	change
/data/orandea/test/aaa vs /data/orandea/impl/bbb	+52%
/foo/bar/baz/quux vs /var/log	+37%
/foo/bar/baz/quux vs /	+25%
/foo/bar/baz/quux vs itself	+5%
/ vs /	+3%
/var vs /bin	~0%
/ vs /var	-9%

test/parallel/test-path-resolve.js, test-path-relative.js, test-path-join.js, test-path-normalize.js, and test-path.js pass. A closed-source coding agent assisted with the implementation.

[nodejs-github-bot]

Review requested:

• @nodejs/path

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.27%. Comparing base (dd5dfb5) to head (62291aa).
⚠️ Report is 48 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #66194    +/-   ##
========================================
  Coverage   90.27%   90.27%            
========================================
  Files         790      790            
  Lines      271651   272544   +893     
  Branches    51842    52039   +197     
========================================
+ Hits       245228   246044   +816     
- Misses      16928    16958    +30     
- Partials     9495     9542    +47     

Files with missing lines	Coverage Δ
lib/path.js	97.50% <100.00%> (+0.02%)	⬆️

... and 65 files with indirect coverage changes

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