Move all geoip-based resolution to DYNA

This eliminates (cross-zone) CNAME chains from our
most common public names, which should significantly
reduce DNS response packet sizes and client/cache
DNS lookup latency.

The simplification of the lookup structure also
makes future changes safer as there aren't
CNAME-based races between the update times of
the individual authservers.

It also removes the redundant copies of various
addresses from the zonefiles, which is DRY-er
and thus avoids faulty partial updates when
addresses change.

Also, root-level lookups (e.g. queries for just
"wikipedia.org") are now geo-distributed, whereas
before they were specified as the direct address
for eqiad (due to lack of CNAME capability at
the zone root).

The net publicly-visible change for all geoip-resolved
hostnames should look like this example:

OLD behavior (2x CNAMEs -> 2x queries, cross-zone):
-----------------------------------------------------
$ dig +short @ns0.wikimedia.org en.wikipedia.org
text-lb.wikimedia.org.
$ dig +short @ns0.wikimedia.org text-lb.wikimedia.org
text-lb.eqiad.wikimedia.org.
208.80.154.224

NEW behavior (direct address result):
-----------------------------------------------------
$ dig +short @ns0.wikimedia.org en.wikipedia.org
208.80.154.224

Change-Id: Iefae74d8d268b72cc24377877b26016bcf995512