Make dnsupdate go back to using dnsjava 2.x

Currently the build breaks due to a surprise migration to dnsjava 1.6.4,
which is not available in Maven. dnsjava 2.x is available internally,
but it jarjar's the package name. So we'll need to deal with that the
same way we deal with the Objectify package rename.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122447929

java/google/registry/dns/writer/dnsupdate/DnsUpdateWriter.java

@@ -195,16 +195,13 @@ public class DnsUpdateWriter implements DnsWriter {
   }
 
   private RRset makeV6AddressSet(String hostName, Iterable<InetAddress> addresses)
-      throws TextParseException, IOException {
+      throws TextParseException {
     RRset addressSet = new RRset();
     for (InetAddress address : addresses) {
       if (address instanceof Inet6Address) {
         AAAARecord record =
             new AAAARecord(
-                toAbsoluteName(hostName),
-                DClass.IN,
-                dnsTimeToLive.getStandardSeconds(),
-                new org.xbill.DNS.Inet6Address(address.getAddress()));
+                toAbsoluteName(hostName), DClass.IN, dnsTimeToLive.getStandardSeconds(), address);
         addressSet.addRR(record);
       }
     }