Remove the deprecated --enable-cri flag

Except for rkt, CRI is the default and only integration point for
container runtimes.

pkg/kubelet/kubelet_node_status_test.go

@@ -812,8 +812,6 @@ func TestUpdateNodeStatusWithRuntimeStateError(t *testing.T) {
 	kubelet.updateRuntimeUp()
 	checkNodeStatus(v1.ConditionFalse, "KubeletNotReady")
 
-	// Test cri integration.
-	kubelet.kubeletConfiguration.EnableCRI = true
 	fakeRuntime.StatusErr = nil
 
 	// Should report node not ready if runtime status is nil.