[tox] fix local install check
D1390 accidentally just turned off the check everywhere - so a handful of prod module use had crept in.
This introduces unix/windows variance to the tox envs so we can use that to gate things.
Test Plan: buildkite and azure
Reviewers: max, nate, prha
Reviewed By: nate, prha
Differential Revision: https://dagster.phacility.com/D2144