Replace docker-fixtures with testcontainers

[timja]

docker-fixtures has been deprecated for a long time, https://www.testcontainers.org is the recommended replacement.

We should switch to it.

[jtnord]

there are issues with testcontainers - I would not recommend switching right away, or this PR should be inlined.

[olamy]

or upgrade to junit5 and simply use @Testcontainers(disabledWithoutDocker = true) ?

[jtnord]

or upgrade to junit5 and simply use @Testcontainers(disabledWithoutDocker = true) ?

The issue with this (and the former PR) is that it will skip the entire test class/suite and not just the test that requires the docker container. (so a larger refactoring of tests would likely be needed, as we routinely mix containerized and non containerized in the same class). Additionally if you skip a class/suite then Jenkins won't know it is skipped in the Junit report so it won't mark the 5 tests in a class as skipped (it will if you skip at the test level).

Given we regressed docker support and no one noticed for quite some time - I would be hesitant of not recording tests as skipped so it stands out like Guliver in Lilliput