Revert "Champ related cleanups and refactoring"

[colinux]

Reverts #10711

https://demarches-simplifiees.sentry.io/issues/5775197801/
https://demarches-simplifiees.sentry.io/issues/5775191032/

[codecov]

Codecov Report

Attention: Patch coverage is 98.14815% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.16%. Comparing base (7693d21) to head (e7443c2).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
app/models/procedure.rb	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10728      +/-   ##
==========================================
- Coverage   84.60%   82.16%   -2.44%     
==========================================
  Files        1119     1119              
  Lines       24756    24910     +154     
  Branches     4612     4582      -30     
==========================================
- Hits        20945    20468     -477     
- Misses       3811     4442     +631     

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