generic ephemeral volume: graduation to GA

The feature gate gets locked to "true", with the goal to remove it in two
releases.

All code now can assume that the feature is enabled. Tests for "feature
disabled" are no longer needed and get removed.

Some code wasn't using the new helper functions yet. That gets changed while
touching those lines.

pkg/scheduler/framework/plugins/nodevolumelimits/csi_test.go

@@ -546,13 +546,6 @@ func TestCSILimits(t *testing.T) {
 			test:             "should not count in-tree and count csi volumes if migration is disabled (when scheduling in-tree volumes)",
 		},
 		// ephemeral volumes
-		{
-			newPod:      ephemeralVolumePod,
-			filterName:  "csi",
-			driverNames: []string{ebsCSIDriverName},
-			test:        "ephemeral volume feature disabled",
-			wantStatus:  framework.NewStatus(framework.Error, "volume xyz is a generic ephemeral volume, but that feature is disabled in kube-scheduler"),
-		},
 		{
 			newPod:           ephemeralVolumePod,
 			filterName:       "csi",
@@ -657,8 +650,6 @@ func TestCSILimits(t *testing.T) {
 				scLister:             getFakeCSIStorageClassLister(scName, test.driverNames[0]),
 				randomVolumeIDPrefix: rand.String(32),
 				translator:           csitrans.New(),
-
-				enableGenericEphemeralVolume: test.ephemeralEnabled,
 			}
 			gotStatus := p.Filter(context.Background(), nil, test.newPod, node)
 			if !reflect.DeepEqual(gotStatus, test.wantStatus) {