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/kubelet/kubelet_pods_test.go

@@ -38,10 +38,8 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/diff"
-	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	core "k8s.io/client-go/testing"
 	"k8s.io/client-go/tools/record"
-	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	netutils "k8s.io/utils/net"
 
 	// TODO: remove this import if
@@ -49,7 +47,6 @@ import (
 	// to "v1"?
 
 	_ "k8s.io/kubernetes/pkg/apis/core/install"
-	"k8s.io/kubernetes/pkg/features"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	containertest "k8s.io/kubernetes/pkg/kubelet/container/testing"
 	"k8s.io/kubernetes/pkg/kubelet/cri/streaming/portforward"
@@ -2979,13 +2976,12 @@ func TestGetPortForward(t *testing.T) {
 
 func TestHasHostMountPVC(t *testing.T) {
 	type testcase struct {
-		pvError          error
-		pvcError         error
-		expected         bool
-		podHasPVC        bool
-		pvcIsHostPath    bool
-		podHasEphemeral  bool
-		ephemeralEnabled bool
+		pvError         error
+		pvcError        error
+		expected        bool
+		podHasPVC       bool
+		pvcIsHostPath   bool
+		podHasEphemeral bool
 	}
 	tests := map[string]testcase{
 		"no pvc": {podHasPVC: false, expected: false},
@@ -3005,16 +3001,9 @@ func TestHasHostMountPVC(t *testing.T) {
 			expected:      true,
 		},
 		"enabled ephemeral host path": {
-			podHasEphemeral:  true,
-			pvcIsHostPath:    true,
-			ephemeralEnabled: true,
-			expected:         true,
-		},
-		"disabled ephemeral host path": {
-			podHasEphemeral:  true,
-			pvcIsHostPath:    true,
-			ephemeralEnabled: false,
-			expected:         false,
+			podHasEphemeral: true,
+			pvcIsHostPath:   true,
+			expected:        true,
 		},
 		"non host path pvc": {
 			podHasPVC:     true,
@@ -3024,7 +3013,6 @@ func TestHasHostMountPVC(t *testing.T) {
 	}
 
 	run := func(t *testing.T, v testcase) {
-		defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.GenericEphemeralVolume, v.ephemeralEnabled)()
 		testKubelet := newTestKubelet(t, false)
 		defer testKubelet.Cleanup()
 		pod := &v1.Pod{