chore(pypi): remove unused config settings code

[aignas]

Summary:

• Remove unused pip_* config settings since they have been no op for a while.
• The code was experimental, so it is likely nobody relied heavily on those things.
• Only leave the OSX version flag - we may want to rename that in the future.

Related #260.

[gemini-code-assist]

Code Review

This pull request streamlines the pip integration by removing the enable_pipstar feature, experimental_target_platforms attribute, and legacy configuration flags, while migrating entry point generation to py_console_script_binary. Review feedback highlights dead code regarding the extras parameter in wheel_installer.py and suggests a more robust method for Python version detection in pip_repository.bzl.

[rickeylev]

Remove unused pip_* config settings since they have been no op for a while.

These are unused? I thought the intent was to use them to allow dependency selection when requirement env markers can't do so. e.g., given requirements_musl.txt and requirements_glibc.txt, one would set --pip_lib=musl|glibc to pick between the two closures.

[aignas]

Remove unused pip_* config settings since they have been no op for a while.

These are unused? I thought the intent was to use them to allow dependency selection when requirement env markers can't do so. e.g., given requirements_musl.txt and requirements_glibc.txt, one would set --pip_lib=musl|glibc to pick between the two closures.

This was like that initially, but in actuality, the musl selection has to be done through the platforms in the pip.default, because the requirements here need to be provided by the user, i.e. is it OK to fall back to glibc wheels, is it not?

By the way, these flags that I am removing here were for selecting the wheel based on the libc version that one may have on different systems, but modelling that is always really difficult.