As approved in StrimziProposal#77, ZooKeeper support should be removed after Kafka 3.9 / before adding support for Kafka 4.0. This issue should cover removing ZooKeeper:

• From the code
• From the docs
• From the examples
• Remove the KRaft migration code and docs
• Deprecate the ZooKeeper parts of the CRDs
• Deprecate the other unused CRD parts -> replicas and storage in the Kafka section
• Deprecate / remove methods from KAfkaResources class not using node pools such as kafkaPodName
• etc.

System tests are covered by a separate issue.