Remove deprecated internal converters

Author: rmoff

kafka-to-database/docker-compose.yml

@@ -79,8 +79,6 @@ services:
       CONNECT_KEY_CONVERTER_SCHEMA_REGISTRY_URL: 'http://schema-registry:8081'
       CONNECT_VALUE_CONVERTER: io.confluent.connect.avro.AvroConverter
       CONNECT_VALUE_CONVERTER_SCHEMA_REGISTRY_URL: 'http://schema-registry:8081'
-      CONNECT_INTERNAL_KEY_CONVERTER: "org.apache.kafka.connect.json.JsonConverter"
-      CONNECT_INTERNAL_VALUE_CONVERTER: "org.apache.kafka.connect.json.JsonConverter"
       CONNECT_LOG4J_ROOT_LOGLEVEL: "INFO"
       CONNECT_LOG4J_LOGGERS: "org.apache.kafka.connect.runtime.rest=WARN,org.reflections=ERROR"
       CONNECT_CONFIG_STORAGE_REPLICATION_FACTOR: "1"