Switch to github.com/coreos/go-systemd/v22 and drop older package

- We use the new v22 module released on May 10
- We drop the unmaintained `github.com/coreos/pkg`

Signed-off-by: Davanum Srinivas <davanum@gmail.com>

test/e2e_node/summary_test.go

@@ -31,7 +31,7 @@ import (
 	e2ekubectl "k8s.io/kubernetes/test/e2e/framework/kubectl"
 	e2evolume "k8s.io/kubernetes/test/e2e/framework/volume"
 
-	systemdutil "github.com/coreos/go-systemd/util"
+	systemdutil "github.com/coreos/go-systemd/v22/util"
 	"github.com/onsi/ginkgo"
 	"github.com/onsi/gomega"
 	"github.com/onsi/gomega/gstruct"