[3.13] gh-122136: test_asyncio: Don't fail if the kernel buffers more data than advertised (GH-123423) (#123443)

gh-122136: test_asyncio: Don't fail if the kernel buffers more data than advertised (GH-123423)
(cherry picked from commit b379f1b26c1e89c8e9160b4dede61b980cc77be6)

Co-authored-by: Petr Viktorin <encukou@gmail.com>