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/volumebinding/volume_binding.go

@@ -69,11 +69,10 @@ func (d *stateData) Clone() framework.StateData {
 // In the Filter phase, pod binding cache is created for the pod and used in
 // Reserve and PreBind phases.
 type VolumeBinding struct {
-	Binder                               SchedulerVolumeBinder
-	PVCLister                            corelisters.PersistentVolumeClaimLister
-	GenericEphemeralVolumeFeatureEnabled bool
-	scorer                               volumeCapacityScorer
-	fts                                  feature.Features
+	Binder    SchedulerVolumeBinder
+	PVCLister corelisters.PersistentVolumeClaimLister
+	scorer    volumeCapacityScorer
+	fts       feature.Features
 }
 
 var _ framework.PreFilterPlugin = &VolumeBinding{}
@@ -131,7 +130,7 @@ func (pl *VolumeBinding) podHasPVCs(pod *v1.Pod) (bool, error) {
 		switch {
 		case vol.PersistentVolumeClaim != nil:
 			pvcName = vol.PersistentVolumeClaim.ClaimName
-		case vol.Ephemeral != nil && pl.GenericEphemeralVolumeFeatureEnabled:
+		case vol.Ephemeral != nil:
 			pvcName = ephemeral.VolumeClaimName(pod, &vol)
 			isEphemeral = true
 		default:
@@ -402,10 +401,9 @@ func New(plArgs runtime.Object, fh framework.Handle, fts feature.Features) (fram
 		scorer = buildScorerFunction(shape)
 	}
 	return &VolumeBinding{
-		Binder:                               binder,
-		PVCLister:                            pvcInformer.Lister(),
-		GenericEphemeralVolumeFeatureEnabled: fts.EnableGenericEphemeralVolume,
-		scorer:                               scorer,
-		fts:                                  fts,
+		Binder:    binder,
+		PVCLister: pvcInformer.Lister(),
+		scorer:    scorer,
+		fts:       fts,
 	}, nil
 }