flink-playgrounds is using a buggy zookeeper

The flink-playgrounds [1] is using a buggy zookeeper image from docker hub, and thus the kafka can never connect to the zookeeper server.

How to reproduce the bug?

For example, after running "docker-compose up -d" in operations-playground [2], we can observe in Flink web UI that the job will in "restarting" state soon, and both "zookeeper" and "kafka" are stopped.

I noticed that the used "wurstmeister/zookeeper:3.4.6" image was published in 7 years ago, and it is badly documented. In my test, switching to "bitnami/zookeeper:3.7.1" can solve this problem.

Also, I think it would be better to discard images published by wurstmeister, since they are not updated frequently (and there buggy), and we should switch to bitnami.

 [1]https://github.com/apache/flink-playgrounds

 [2] https://github.com/apache/flink-playgrounds/tree/master/operations-playground)