refactor: Remove decorator dependency from utils

[microamp]

Fixes #5654

I have noticed that decorator is also being used in debug.py, so it will remain in requirements.txt for now.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 88.94%. Comparing base (187c2c5) to head (0f76a19).
Report is 62 commits behind head on main.

Files	Patch %	Lines
ietf/utils/decorators.py	80.00%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7199      +/-   ##
==========================================
- Coverage   88.98%   88.94%   -0.05%     
==========================================
  Files         291      291              
  Lines       40717    41067     +350     
==========================================
+ Hits        36233    36527     +294     
- Misses       4484     4540      +56     

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[jennifer-richards]

This looks ok - would be good to give the same treatment to debug.py, but that could go into a separate PR.