add specs for logging out saml user

[mattbaumann1]

Add specs for logging out saml user. There was an error in the Rails 6 upgrade that broke the saml logout(#690 ). The error has been fixed, but additional specs should be added to identify issues like this in the future.

[mattbaumann1]

I was having a hard time with this ticket. I have talked with @jpatel about working on this together. This ticket will be put on hold until we can orchestrate that work. Although useful, there are other features that are equally important that will be explored instead.