m2v2: enable/disable Kafka events from conscience conf

and fix memory leaks and disable Kafka events for local bases

To enable Kafka events from conscience configuration, for all namespaces:
  param_option.event_config.meta2 = kafka_enabled=true;kafka_topic=TOPIC

To enable Kafka events from conscience configuration, for a namespace
and all its virtual sub-namespaces:
  param_option.NAMESPACE_event_config.meta2 = kafka_enabled=true;kafka_topic=TOPIC

kafka_topic is optional and defaults to "redc.meta2"

Change-Id: I7ea1094e24e5029cfcad46c031db35ba99f2eb47