gh-148259: make list.remove atomic for non-trivial __eq__ comparison

[KowalskiThomas]

What is this PR?

This PR addresses the bug reported in #148259 where calling rich comparison may result in releasing the GIL which may result in list.remove removing the wrong item from the list.

The PR also updates the tests added for #126033.

• Issue: list.remove is not atomic for non trivial __eq__ comparisons #148259

[colesbury]

Please add a NEWS entry (https://devguide.python.org/getting-started/pull-request-lifecycle/#how-to-add-a-news-entry) and fix the failing tests.

[picnixz]

The raises parameter is now misleading. Please correct it. In addition, please add tests to list itself. And please also update the docs if they need to.

Overall, I'm not convinced by this change. Mutating the list while doing the comparison is unsafe. We just don't want to crash. But making it raise a RuntimeError does not necessarily makes it better. Otherwise, we need to do it for all other mutable sequences in C to have more or less the same behavior.

cc @rhettinger

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