Add ZOOCFGDIR env variable to ZooKeeper to make scripts work

[lfrancke]

Description

This works around https://issues.apache.org/jira/browse/ZOOKEEPER-4985
If we don't set this variable most of the shell scripts will fail (definitely zkCleanup.sh).
It can be set manually before every call but we do know the location of the config directory so no harm in making it a bit easier.

I didn't think this needed a changelog entry, happy to add if you think otherwise.

Definition of Done Checklist

• Add an entry to the CHANGELOG.md file
• Integration tests ran successfully

[maltesander]

Hmm, we have a rwconfig as well for the real config https://github.com/stackabletech/zookeeper-operator/blob/e370101dfe986e862c0354f6a50471b857d0c078/rust/operator-binary/src/zk_controller.rs#L927.
Its created by the operator though...maybe this should be set in the operator?

[lfrancke]

I'm not sure I understand this to be honest. Is /stackable/config the wrong directory then?

[maltesander]

We basically use the config mounted in /stackable/config, copy that to /stackable/rwconfig to replace/extend the myid etc. A quick glance does not show anything else https://github.com/stackabletech/zookeeper-operator/blob/main/rust/operator-binary/src/command.rs#L3. We do more in other operators.

Thats why the tests probably work fine, just wanted to say that the config file stored in /stackable/config is not the one zookeeper runs with, see https://github.com/stackabletech/zookeeper-operator/blob/e370101dfe986e862c0354f6a50471b857d0c078/rust/operator-binary/src/zk_controller.rs#L955.

And the rwconfig is an empty dir created by the operator.