Use hardcoded IPv4/IPv6 addresses for google-public-dns-a.google.com instead
of freefall.freebsd.org to unbreak the DNS tests

The address allocations for freefall.freebsd.org have changed in the past 4 years.
Use a more stable set of hardcoded addresses for now to make the tests succeed
reliably.

The hostname should be resolved dynamically instead of hardcoding the addresses in
the future. This is just a bandaid.

MFC after: 1 week