Remove rktnetes code

rktnetes is scheduled to be deprecated in 1.10 (#53601). According to
the deprecation policy for beta CLI and flags, we can remove the feature
in 1.11.

Fixes #58721

pkg/kubelet/cadvisor/helpers_linux.go

@@ -38,8 +38,6 @@ func (i *imageFsInfoProvider) ImageFsInfoLabel() (string, error) {
 	switch i.runtime {
 	case types.DockerContainerRuntime:
 		return cadvisorfs.LabelDockerImages, nil
-	case types.RktContainerRuntime:
-		return cadvisorfs.LabelRktImages, nil
 	case types.RemoteContainerRuntime:
 		// This is a temporary workaround to get stats for cri-o from cadvisor
 		// and should be removed.