system_keyspace: Coroutinize get_/set_local_host_id
system_keyspace: Coroutinize get_/set_local_host_id

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla