Unify configuration of KafkaSQL storage to a single approach

[EricWittmann]

There are two ways to configure Kafka security properties. We have some explicit configuration options here:

https://github.com/Apicurio/apicurio-registry/blob/main/app/src/main/java/io/apicurio/registry/storage/impl/kafkasql/KafkaSqlFactory.java#L101

...and there is a general way to configure producers/consumers here:

https://github.com/Apicurio/apicurio-registry/blob/main/app/src/main/java/io/apicurio/registry/storage/impl/kafkasql/KafkaSqlFactory.java#L83

The old operator has been using the second approach, and I think we should remove the specific configuration and instead document how to use the general properties feature.