[3.12] gh-132415: Use shutil.which() in missing_compiler_executable() (GH-132906) (GH-135392)

Replace deprecated distutils.spawn.find_executable() with
shutil.which() in missing_compiler_executable() of test.support.
(cherry picked from commit de6482eda3a46cc9c9a03fb9ba57295ab99b4722)

Co-authored-by: Victor Stinner <vstinner@python.org>