Remove container type from kubelet runtime labels

We've changed the Ephemeral Containers API, and container type will no
longer be required. Since this is the only feature using it, remove it.

This reverts commit ba6f31a6c6.

pkg/kubelet/kuberuntime/kuberuntime_container_test.go

@@ -323,7 +323,7 @@ func TestLifeCycleHook(t *testing.T) {
 		}
 
 		// Now try to create a container, which should in turn invoke PostStart Hook
-		_, err := m.startContainer(fakeSandBox.Id, fakeSandBoxConfig, testContainer, testPod, fakePodStatus, nil, "", kubecontainer.ContainerTypeRegular)
+		_, err := m.startContainer(fakeSandBox.Id, fakeSandBoxConfig, testContainer, testPod, fakePodStatus, nil, "")
 		if err != nil {
 			t.Errorf("startContainer erro =%v", err)
 		}