PoC: Rewrite authentication tests

[monteiro-renato]

Description

Re-writing: https://github.com/Altinn/altinn-authentication/tree/main/test/Altinn.Platform.Authentication.SystemIntegrationTests

and improving scalability of : https://github.com/Altinn/altinn-authentication/tree/main/test/Altinn.Platform.Authentication.PerformanceTests

Started work in my own fork: https://github.com/monteiro-renato/altinn-authentication/tree/rewrite-integration-tests-into-k6-tests by re-implementing the SystemRegister component tests.

Maintaining Vegard and Dagfinn up to date. So far they seem to agree it looking better but have some reservations on how to re-use tests for performance tests. I'm now going to implement one of Dagfinn's tests my way to show how it can be achieved.

Additional Information

No response

[monteiro-renato]

Somewhat related to: #1150
(I was hoping I didn't have to do this myself 😅)