run_tests: Switch disutils -> site, for Py3.8

[seemethere]

distuils was absorbed into the stdlib as part of Python 3.8 which makes
the from setuptools import distutils invalid.

Instead of writing some try / except logic or logic based around Python
versions lets just make it so that you don't have to care at all and use
something that's built into the stdlib for everything.

NOTE: Doesn't work on anything python <= 2.6

CircleCI logs for reference

Jan 28 00:56:59 + echo 'Checking the OpenBLAS is not linked to'
Jan 28 00:56:59 Checking the OpenBLAS is not linked to
Jan 28 00:56:59 + all_dylibs=($(find "$(python -c 'from setuptools import distutils; print(distutils.sysconfig.get_python_lib())')"/torch -name '*.dylib'))
Jan 28 00:56:59 +++ python -c 'from setuptools import distutils; print(distutils.sysconfig.get_python_lib())'
Jan 28 00:56:59 Traceback (most recent call last):
Jan 28 00:56:59   File "<string>", line 1, in <module>
Jan 28 00:56:59 AttributeError: module 'distutils' has no attribute 'sysconfig'
Jan 28 00:56:59 ++ find /torch -name '*.dylib'
Jan 28 00:56:59 find: /torch: No such file or directory

Only really affects macOS

Will hopefully unblock pytorch/pytorch#31948

also includes some whitespace changes since my editor automatically removes trailing whitespace. (sorry, not sorry)

If you're worried about the whitespace changes, here's a diff where it doesn't show them: https://github.com/pytorch/builder/pull/398/files?utf8=%E2%9C%93&diff=split&w=1

Signed-off-by: Eli Uriegas eliuriegas@fb.com