test/e2e: do not use global variable for image

We have "-kube-test-repo-list" command line flag to override the image registry. If we store it in global variable, then that overriding cannot take effect.

And this can cause puzzling bugs, e.g.: containerIsUnused() function will compare incorrect image address.

test/e2e/framework/util.go

@@ -53,7 +53,6 @@ import (
 	"k8s.io/client-go/tools/clientcmd"
 	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
 	watchtools "k8s.io/client-go/tools/watch"
-	imageutils "k8s.io/kubernetes/test/utils/image"
 	netutils "k8s.io/utils/net"
 )
 
@@ -132,14 +131,8 @@ const (
 )
 
 var (
-	// BusyBoxImage is the image URI of BusyBox.
-	BusyBoxImage = imageutils.GetE2EImage(imageutils.BusyBox)
-
 	// ProvidersWithSSH are those providers where each node is accessible with SSH
 	ProvidersWithSSH = []string{"gce", "gke", "aws", "local", "azure"}
-
-	// ServeHostnameImage is a serve hostname image name.
-	ServeHostnameImage = imageutils.GetE2EImage(imageutils.Agnhost)
 )
 
 // RunID is a unique identifier of the e2e run.