The integration tests for event and program in the VEN library rely on a DB created by the sqlx testing framework. This is not ideal, especially if we want to test the integration of our VEN library with a 3rd party VTN. Instead, the tests should rely on a running VTN instance and connect to a predefined URL.
This also requires a predefined set of credentials with associated roles in the VTN, which the tests can rely on. Currently, they are created from the test_user_credentials.sql and applied in the CI before test execution.
The tests must also run serially instead of in parallel, to avoid interference between them.

The tests for resources and ven do that already, though there might be room for improvement on how to design the tests exactly. Especially, a failing test may currently leave the VTN/DB in a different state than before.