authdns: switch to all IPs on all hosts

Under this model, the daemon listens on the ANY-addresses,
and the interfaces are set up so that all of them can
answer any of the public addrs so that routing/anycast is
independent of server config.  If any public DNS service IP
gets routed to any box with role::authdns::server, it will
answer those requests.

Change-Id: Ic64c2a8955dd560234c2fbcc6fd6084e7917baaf