Remove a configuration key that's been long removed
Remove a configuration key that's been long removed

As of https://github.com/rabbitmq/rabbitmq-management/commit/347d551f681e43fe8a8bc330d928f689c2270630

rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website