TNL-328 Cohort/server display auto

[TNL-180](https://openedx.atlassian.net/browse/TNL-180)

hmm.. yes.  I wonder why the code in `test_cohorts.py` doesn't use UserFactory and CohortFactory.  That would eliminate the need to call `cohorts.add_cohort` and `User.objects.create` directly.  Any issues with me updating `test_cohorts.py` to use these factories instead?

But I don't see how this applies to the `verify_lists_expected_cohorts` method, however, since it doesn't actually create any cohort entries in the database.