authdns: switch final migration bits

Switch to the service names and add monitoring of the new servers.

Change-Id: I5e298f5804ba16de1f6311acb28cc47877d40174
Cleanup dns::auth-server

Not used anymore, get rid of it and associated files/templates.

Change-Id: Ie136e12547e6da5cf21d093fcea4cb87026f8ac1