[Feature] E2E tests for integrations

### Relevant component

refarch-integrations

### Problem description (optional)

Currently the integrations can only be tested with running stack or internally.
For all integrations there should be a full e2e test for easy lifecycling.

### Desired solution

Create e2e tests for all integrations i.e. with testcontainers.

Start by inspecting refarch-integrations and inventorying its integrations and any existing internal or stack-based tests. Evaluate how testcontainers can provide repeatable lifecycle coverage for each integration. Done means every integration has a full end-to-end test that starts and cleans up its dependencies.

Written by the indexing model from the issue text.