tests: Replaces dnsutils image used with agnhost (part 4)

Quite a few images are only used a few times in a few tests. Thus,
the images are being centralized into the agnhost image, reducing
the number of images that have to be pulled and used.

This PR replaces the usage of the following images with agnhost:

- dnsutils

dnsmasq is a Linux specific binary. In order for the tests to also
pass on Windows, CoreDNS should be used instead.

test/utils/image/manifest.go

@@ -70,6 +70,7 @@ func initReg() RegistryList {
 		DockerLibraryRegistry:   "docker.io/library",
 		DockerGluster:           "docker.io/gluster",
 		E2eRegistry:             "gcr.io/kubernetes-e2e-test-images",
+		// TODO: After the domain flip, this should instead be k8s.gcr.io/k8s-artifacts-prod/e2e-test-images
 		PromoterE2eRegistry:     "us.gcr.io/k8s-artifacts-prod/e2e-test-images",
 		InvalidRegistry:         "invalid.com/invalid",
 		GcRegistry:              "k8s.gcr.io",
@@ -139,8 +140,6 @@ const (
 	CudaVectorAdd
 	// CudaVectorAdd2 image
 	CudaVectorAdd2
-	// Dnsutils image
-	Dnsutils
 	// EchoServer image
 	EchoServer
 	// Etcd image
@@ -216,7 +215,6 @@ func initImageConfigs() map[int]Config {
 	configs[CheckMetadataConcealment] = Config{e2eRegistry, "metadata-concealment", "1.2"}
 	configs[CudaVectorAdd] = Config{e2eRegistry, "cuda-vector-add", "1.0"}
 	configs[CudaVectorAdd2] = Config{e2eRegistry, "cuda-vector-add", "2.0"}
-	configs[Dnsutils] = Config{e2eRegistry, "dnsutils", "1.1"}
 	configs[EchoServer] = Config{e2eRegistry, "echoserver", "2.2"}
 	configs[Etcd] = Config{gcRegistry, "etcd", "3.4.3"}
 	configs[GlusterDynamicProvisioner] = Config{dockerGluster, "glusterdynamic-provisioner", "v1.0"}