[3.9] bpo-42146: Fix memory leak in subprocess.Popen() in case of uid/gid overflow...

[3.9] bpo-42146: Fix memory leak in subprocess.Popen() in case of uid/gid overflow (GH-22966) (GH-22980)

Fix memory leak in subprocess.Popen() in case of uid/gid overflow

Also add a test that would catch this leak with `--huntrleaks`.

Alas, the test for `extra_groups` also exposes an inconsistency
in our error reporting: we use a custom ValueError for `extra_groups`,
but propagate OverflowError for `user` and `group`.
(cherry picked from commit c0590c0033e86f98cdf5f2ca6898656f98ab4053)

Co-authored-by: Alexey Izbyshev <izbyshev@ispras.ru>
Automerge-Triggered-By: GH:gpshead