Sunset ATS

[Swatinem]

ATS has not provided the value that it set out to do, there is barely anyone using it, and its internal implementation is bad for performance, and blocking further improvements.

In particular, I would like to clean up all the labels and datapoints related code from the Report classes, which should simplify things and improve performance, as well as open up more opportunities down the road, in particular make any kind of rewrite it in Rust a lot simpler.

Stop using it ourselves

• Remove ATS-related configuration codecov-api#1166
• Remove ATS-related configuration shared#518
• Remove ATS-related configuration codecov-cli#644
• Remove ATS-related workflow gha-workflows#43

Clearly deprecate the feature

• Stop advertising it and the related commands / flags within codecov-cli
• Mark the feature as clearly deprecated in the docs
• Mark the github action https://github.com/codecov/codecov-ats as deprecated
• Reach out to the existing users (if there are any) about the deprecation
• A list of owner/repo using this feature is here: https://metabase.codecov.dev/question/273-labelanalysis-users

Profit

• Remove all label-analysis / ats related endpoints and code from api
• Remove all label-analysis / ats related tasks and code from worker
• Remove all label-analysis / ats related commands and code from cli
• Remove labels related code from the Report classes, the ReportBuilder, as well as the serialized format
• Possibly remove the EditableReport class completely, as I believe it primarily exists to deal with labels?¿?
• 🎉 profit 🎉

[Swatinem]

One question would be whether we could already start removing some of the backend code before waiting for a grace period to allow the few remaining users to move off of this feature.

In that way, we would just return a "good default", however that would look like, instead of computing the actual precise results.