Investigate and fix any kafkacat tests that rely on -e flag

[sscaling]

Currently the there are a set of tests that validate behaviour using kafkacat - they can be seen https://github.com/wurstmeister/kafka-docker/blob/master/test/docker-compose.yml#L34-L45.

They rely on kafkacat to stop consuming when the last offset is reached - however, in the confluentinc/cp-kafkacat:latest image, the behaviour has changed.

To unblock PRs, I have fixed the version to 5.0.0 which appears to work as expected. However, we should investigate why, raise an issue with the upstream repo if necessary, or fix the tests.

[roadSurfer]

This would appear to be the underlying issue:
edenhill/kcat#86

[sscaling]

@roadSurfer - the change happened fairly recently. Looking at the recent changes (within a few months), this looks more suspect confluentinc/librdkafka@f561f2c