This change removes the deprecated methods from the realm class. These methods include
blocking authentication and lookup and the lookup supported method.
Original commit: elastic/x-pack-elasticsearch@cff21e21ee
This is a followup from elastic/elasticsearchelastic/elasticsearch#21590 and needs to be
committed first or at the same time since netty_3 is removed
Original commit: elastic/x-pack-elasticsearch@131d74dd6b