chore: remove more dead code

[jennifer-richards]

Note the removal of ietf.utils.aliases - I did not see any references to the module but wanted to call it out because it smells like something that might have been used in an obscure way from outside the project.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.01%. Comparing base (c7f6bde) to head (08eb3f1).
Report is 177 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8208      +/-   ##
==========================================
+ Coverage   88.78%   89.01%   +0.22%     
==========================================
  Files         296      303       +7     
  Lines       41320    41287      -33     
==========================================
+ Hits        36687    36750      +63     
+ Misses       4633     4537      -96     

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