* 'gleb/gossip-cleanup-v3' of github.com:scylladb/scylla-dev:
gossiper: start failure_detector_loop on shard 0 only
gossiper: use 1 seconds instead of 1000 milliseconds
gossiper: remove unused code
gossiper: co-routinize do_send_ack2_msg
gossiper: do not needlessly call get_endpoint_state_ptr in handle_major_state_change
gossiper: fix weird logic in get_live_members
gossiper: drop unneeded this->
gossiper: fold get_or_create_endpoint_state into my_endpoint_state
gossiper: co-routinize do_send_ack_msg