[build] Skip javadoc task for pulsar-client-kafka-compact modules (#5836)

*Motivation*

pulsar-client-kafka-compact depends on pulsar-client implementation hence it pulls in
protobuf dependencies. This results in `class file for com.google.protobuf.GeneratedMessageV3 not found`
errors when generating javadoc for those modules.

*Modifications*

Skip javadoc tasks for these modules. Because:

- pulsar-client-kafka-compact is a kafka wrapper. Kafka already provides javadoc for this API.
- we didn't publish the javadoc for this module.
1 file changed