Arktos-vm-runtime uses "virtlet-eth0" as IFname to CNI

[yb01]

this ended up as the CNI call to the Mizar as below. currently mizar has issue and only allow "eth0" as the IFName. we need to see if we need to either fix the limitation in Mizar of workaround it in arktos-runtime, i.e. hard-coded eth0 in the cniRuntimeConfig.

 mizarcni.go:57] Network variables: {"Command":"ADD","ContainerID":"9fd465eb-8d8a-4fe2-bcea-c98f82db48fc","NetNS":"/var/run/netns/9fd465eb-8d8a-4fe2-bcea-c98f82db48fc","IfName":"virtlet-eth0","CniPath":"/opt/cni/bin","K8sPodNamespace":"default","K8sPodName":"vmdefault","K8sPodTenant":"system","CniVersion":"0.3.1","NetworkName":"mizarcni","Plugin":"mizarcni"}

func (c *realClient) cniRuntimeConf(podID, podName, podNs, podTenant, vpc, nics, cniArgs string) *libcni.RuntimeConf {
	r := &libcni.RuntimeConf{
		ContainerID: podID,
		NetNS:       PodNetNSPath(podID),
		IfName:      "virtlet-eth0",
	}
	if podName != "" && podNs != "" {
		r.Args = [][2]string{
			{"IgnoreUnknown", "1"},
			{"K8S_POD_TENANT", podTenant},
			{"K8S_POD_NAMESPACE", podNs},
			{"K8S_POD_NAME", podName},
			{"K8S_POD_INFRA_CONTAINER_ID", podID},
			{"VPC", vpc},
			{"NICs", nics},
		}

		if kvs, err := toCNIArgs(cniArgs); err == nil {
			for k, v := range kvs {
				r.Args = append(r.Args, [2]string{k, v})
			}
		}
	}
	return r
}

[yb01]

the hard-coded ifName is not ideal. but this is OK for CNI's perspective. so this is not a functionality issue.