Refactor e2e tests for better test coverage

[reinkrul]

We currently have the "RFC021" e2e-test that provides the most coverage, but still not enough. At the same time, it was never intended as the "one test that tests databases".

Should we create a new e2e-test that tests:

• all steps (including now missing revocation) for a particular application flow/use case
• on all supported databases

Then we can simplify RFC021 test to cover only RFC021 (and not discovery and statuslist functionality, like it currently does).