chore!: remove legacy repo support (#19768)

[crenshaw-dev]

Closes #19768

TODO:

• docs
• make sure I haven't lost important test coverage

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[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 55.34%. Comparing base (ef55ba5) to head (929c695).
Report is 19 commits behind head on master.

Files with missing lines	Patch %	Lines
util/db/repository.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #21249      +/-   ##
==========================================
+ Coverage   55.17%   55.34%   +0.16%     
==========================================
  Files         337      336       -1     
  Lines       57057    56388     -669     
==========================================
- Hits        31483    31208     -275     
+ Misses      22870    22537     -333     
+ Partials     2704     2643      -61     

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