[BUG] Kafka Connect extension loaded even if not needed

[dlvenable]

Describe the bug

When running a Data Prepper pipeline without any Kafka Connect plugins, I see logs for the Kafka extension.

2023-10-27T14:44:40.828 [main] INFO  org.opensearch.dataprepper.plugins.kafka.extension.KafkaClusterConfigExtension - Applying Kafka Cluster Config Extension.
2023-10-27T14:44:40.829 [main] INFO  org.opensearch.dataprepper.plugins.kafkaconnect.extension.KafkaConnectConfigExtension - Applying Kafka Connect Config Extension.

To Reproduce

Run a pipeline.

Expected behavior

If the Kafka extension is not needed, then don't load it. This should happen for all extensions.

[dlvenable]

We shouldn't need this in 2.6.0 if we exclude the Kafka Connect plugins from that build. This should exclude this extension.