tools: use tokenless Codecov uploads

[targos]

Refs: https://docs.codecov.com/docs/codecov-tokens#uploading-without-a-token

I already enabled it in the Codecov settings for the nodejs org.

[nodejs-github-bot]

Review requested:

• @nodejs/actions

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.00%. Comparing base (a2edde4) to head (603dc9e).
Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #55943      +/-   ##
==========================================
- Coverage   88.49%   88.00%   -0.49%     
==========================================
  Files         653      653              
  Lines      187735   187728       -7     
  Branches    36181    35871     -310     
==========================================
- Hits       166141   165218     -923     
- Misses      14819    15695     +876     
- Partials     6775     6815      +40     

see 98 files with indirect coverage changes

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests
• JS Bundle Analysis - Avoid shipping oversized bundles