[cyclocomp_linter] tweak: use native lambda, don't keep source

[MichaelChirico]

Seen while working on #2912

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.24%. Comparing base (d6afa52) to head (21d5d23).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2984   +/-   ##
=======================================
  Coverage   99.24%   99.24%           
=======================================
  Files         128      128           
  Lines        7267     7267           
=======================================
  Hits         7212     7212           
  Misses         55       55           

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