The "[sig-network] DNS HostNetwork should resolve DNS of partial qualified
names for services on hostNetwork pods with dnsPolicy:
ClusterFirstWithHostNet" test assumes that a service named "kube-dns"
exists in the "kube-system" namespace. This assumption is valid if the
cluster was configured using kubeadm, but the assumption may be invalid
otherwise.
As the test uses dnsPolicy: ClusterFirst (as opposed to dnsPolicy: None),
it does not need to specify the name server in dnsConfig. Omitting
dnsConfig.nameservers obviates the need to look up the service.
Follow-up to commit add4652352.
* test/e2e/network/dns.go: Don't look up or use the kube-dns cluster IP
address as it might not exist on clusters that were not configured using
kubeadm.