Add randomization to test suite to find test isolation problems

[jacobtylerwalls]

We can tackle test isolation issues in future work by adding a pytest plugin or some other solution for shuffling test cases.

Originally posted by @jacobtylerwalls in #9041 (comment)

I'm familiar with the Django test runner's --shuffle option, but perhaps we can evaluate pytest-random-order or other plugins.

[Pierre-Sassoulas]

It's possible that in the case of #9041 the problem was the sys.argv content. Locally pytest does not work, vs pytest -k unbalan works, but in the CI it's python -m pytest --durations=10 --benchmark-disable --cov --cov-report= tests/ and it also did not work.