[3.12] gh-119311: Fix name mangling with PEP 695 generic classes (#119464)#119644

Yhg1s merged 3 commits intopython:3.12python/cpython:3.12from

JelleZijlstra:backport-a9a74da-3.12JelleZijlstra/cpython:backport-a9a74da-3.12Copy head branch name to clipboard