delete unnecessary testproject and broken test

[cosmicexplorer]

Problem

Spent a bit more time thinking after #6493 and there's no reason we need to test the case of a pants_requirement() in a python_dist()'s setup_requires -- as @jsirois said in #6490, these are both well-tested at lower levels, and the increase in CI time alone, even if it worked, is enough to make this removal-worthy.

Solution

• Delete examples/src/python/example/python_distribution/hello/pants_setup_requires/ and test_pants_requirement_setup_requires_version, which is the broken test that depends on it.

Result

This was intentionally separated from #6493 so we can have absolutely no fear of merging that first to fix CI. Resolves #6490.

[jsirois]

Yay!

[cosmicexplorer]

Rebased after merging #6493, waiting for ci to go green again.

[cosmicexplorer]

The unittest import in the python_dist integration test is now unused (it was only added to skip the test). The only reason I mention it is that I'm pretty sure I didn't disable or comment out the pre-commit hook, which should have caught that. I haven't been able to repro it.

Actually, I think it's because the pre-commit hook doesn't seem to run when editing an intermediate commit during a rebase. Is that true? This page on the git site doesn't answer the question but could imply by omission that pre-commit would run on every commit.

It's not important, I just can't see at all how that could have gotten past the pre-commit hook, I don't recall having to comment it out or remove it at all today.