Distutils hack still causing test failures in CPython

[jaraco]

In python/cpython#91169, we learn that despite #2965 and #3007, when the tests are run outside of the source directory, some tests will still fail because Setuptools is unable to detect that these tests are implicated.

For at least three of these tests (test_distutils and on Python 3.9, test_importlib and test_peg_generator), these issues may be avoidable by further suppressing the supplying of distutils.

test_bdb is also affected, but cannot be addressed due to python/cpython#93951.