refactor: use standard_lib argument to get_python_lib

[Lewiscowles1986]

Reading through docs and following code, it seems there is a standard_lib boolean argument, which strips site-packages. While I've not been able to replicate needing that, it was present in the original code and may represent an upgrade path blocker for folks.

Lets keep that but allow distutils to own that, rather than manually stripping path that has been built-up in the get_python_lib call