replace commitment_signed_dance macro in test utils

[elnosh]

This removes the commitment_signed_dance macro and replaces it with the calls to the appropriate functions.

[ldk-reviews-bot]

I've assigned @valentinewallace as a reviewer!
I'll wait for their review and will help manage the review process.
Once they submit their review, I'll check if a second reviewer would be helpful.

[codecov]

Codecov Report

❌ Patch coverage is 99.70238% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 89.34%. Comparing base (e42e74e) to head (1bbc692).
⚠️ Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
lightning/src/ln/payment_tests.rs	98.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4214      +/-   ##
==========================================
+ Coverage   89.33%   89.34%   +0.01%     
==========================================
  Files         180      180              
  Lines      138055   138122      +67     
  Branches   138055   138122      +67     
==========================================
+ Hits       123326   123401      +75     
+ Misses      12122    12117       -5     
+ Partials     2607     2604       -3     

Flag	Coverage Δ
fuzzing	33.57% <0.00%> (-0.01%)	⬇️
tests	88.73% <99.70%> (+0.01%)	⬆️

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[TheBlueMatt]

Yay! Thanks! Might be worth going back and adding better documentation (and comments) on the methods that are there and thinking about whether there's some better way to communicate what's happening in method names.