Decide what to do with the regression tests which do not work anymore

Do we want regression tests?

Do we want end-to-end tests? -> Yes but simple and integrated in CI

Start by reviewing the regression tests that no longer work and the existing end-to-end test setup, then inspect how tests are integrated into CI. Clarify whether regression tests should remain and define a simple end-to-end test approach that runs in CI; the decision and resulting test plan should be documented.

Written by the indexing model from the issue text.