CloudFlare's public recursive DNS resolvers are available at
multiple anycast addresses. For some reason 1.1.1.1 is unreachable
from parts of OVH's BHS1 region, but 1.0.0.1 seems to be
consistently reachable. Swap this for improved reliability.
Depends-On: https://review.opendev.org/655687
Change-Id: I403961828f4af3f121a6fa2193a933c9fc4a7bc7
f113b2051b