Set REQUIRE_COURSE_EMAIL_AUTH to True

In production this value is True.

Changing this config file means that developers, by default, will see course email in their local dev and sandbox environments. This is important for full testing of released features. We shouldn't hide a feature we use on prod behind a feature flag locally.
@sarina  When the manual testers found those issues, did anyone look into adding/revising tests to prevent similar issues from making it all the way to manual tests again in the future?

I don't know really know this feature or the issues with it seen in the past, but it seems like we are missing a few cases in these tests.