refactor PVL unit tests to use test tables & add test cases for remaining cloud providers

plugin/pkg/admission/storage/persistentvolume/label/BUILD

@@ -34,9 +34,10 @@ go_test(
     deps = [
         "//pkg/apis/core:go_default_library",
         "//pkg/kubelet/apis:go_default_library",
-        "//pkg/volume/util:go_default_library",
         "//staging/src/k8s.io/api/core/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/admission:go_default_library",
         "//staging/src/k8s.io/cloud-provider:go_default_library",
     ],

plugin/pkg/admission/storage/persistentvolume/label/admission.go

@@ -158,7 +158,8 @@ func (l *persistentVolumeLabel) Admit(a admission.Attributes) (err error) {
 				if err != nil {
 					return admission.NewForbidden(a, fmt.Errorf("failed to convert label string for Zone: %s to a Set", v))
 				}
-				values = zones.UnsortedList()
+				// zone values here are sorted for better testability.
+				values = zones.List()
 			} else {
 				values = []string{v}
 			}