Updates the codebase to use the new glibc-dns-testing image which replaces
the deprecated jessie-dnsutils image.
This PR depends on the glibc-dns-testing image being available in the
registry (registry.k8s.io/e2e-test-images/glibc-dns-testing:2.0.0).
Signed-off-by: Davanum Srinivas <davanum@gmail.com>