The config.host_id value is loaded early on start, but when the
storage service prepares to join the cluster to replace a node,
it will change that value (with the host id of the target). This
change only affect the system keyspace, but not the config copy
which is a BUG.
fixes: #10243
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>