Update tests requiring the auth api

[FedericoNegri]

Pull Request Template

Description

Some of our tests were failing due to the latest changes in the Keycloak configuration. They relied on repadmin having the manage-users role, which is not the case anymore.

Now, tests that need to create temporary users directly use the KeycloakAdmin client with our default keycloak admin user.

Checklist

Please complete the following checklist before submitting your pull request:

• I have tested these changes locally and verified that they work as intended.
• I have updated any documentation as needed to reflect these changes (if appropriate)
• I have verified that these changes to the best of my knowledge do not introduce any security vulnerabilities.
• Unit tests have been added (if appropriate)
• Test-cases have been added (if appropriate)
• Testing instructions have been added (if appropriate)

[Buzz1167]

I believe this is fine, Michael had said previously that he was using the keycloak account to create users for Kubernetes already which is why he was ok with my dropping permissions on repadmin. I think in general we need more separation of roles, so I like it to allow this special user the only one to make changes to keycloak config and let repadmin just be the admin of the REP projects/UI.

When we have to deploy at a customer site, its quite likely that the customer wants to do some AD integration and their IT wants to control that, but that their IT knows nothing about REP and they want a power user to manage everything else.