Use KubeletRunDirectory instead of hard-coded way

Signed-off-by: Xianglin Gao <xianglin.gxl@alibaba-inc.com>

cmd/kubeadm/app/phases/kubelet/BUILD

@@ -44,6 +44,7 @@ go_test(
     embed = [":go_default_library"],
     deps = [
         "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
+        "//cmd/kubeadm/app/constants:go_default_library",
         "//pkg/kubelet/apis:go_default_library",
         "//pkg/kubelet/apis/kubeletconfig:go_default_library",
         "//pkg/util/version:go_default_library",

cmd/kubeadm/app/phases/kubelet/flags_test.go

@@ -27,6 +27,7 @@ import (
 
 	"k8s.io/api/core/v1"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/utils/exec"
 )
 
@@ -249,7 +250,7 @@ func TestBuildKubeletArgMap(t *testing.T) {
 			expected: map[string]string{
 				"container-runtime":          "remote",
 				"container-runtime-endpoint": "/var/run/containerd.sock",
-				"dynamic-config-dir":         "/var/lib/kubelet/dynamic-config",
+				"dynamic-config-dir":         fmt.Sprintf("%s/dynamic-config", kubeadmconstants.KubeletRunDirectory),
 			},
 		},
 	}