api: drop Resources.Claims from PVC and PVC template

PVC and containers share the same ResourceRequirements struct. The Claims field
in it only makes sense when used in containers. When used in a PVC, the field
should have been rejected by validation. This was overlooked when introducing
it, so now persisted objects might have it set and/or people may have started
to rely on it being accepted even when it has no effect.

Therefore we cannot reject it in validation anymore, but we can still strip
it out on create or update.

pkg/api/pod/util_test.go

@@ -2236,3 +2236,41 @@ func TestValidateTopologySpreadConstraintLabelSelectorOption(t *testing.T) {
 		})
 	}
 }
+
+func TestDropVolumesClaimField(t *testing.T) {
+	pod := &api.Pod{
+		Spec: api.PodSpec{
+			Volumes: []api.Volume{
+				{},
+				{
+					VolumeSource: api.VolumeSource{
+						Ephemeral: &api.EphemeralVolumeSource{},
+					},
+				},
+				{
+					VolumeSource: api.VolumeSource{
+						Ephemeral: &api.EphemeralVolumeSource{
+							VolumeClaimTemplate: &api.PersistentVolumeClaimTemplate{
+								Spec: api.PersistentVolumeClaimSpec{
+									Resources: api.ResourceRequirements{
+										Claims: []api.ResourceClaim{
+											{Name: "dra"},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	DropDisabledPodFields(pod, nil)
+
+	for i, volume := range pod.Spec.Volumes {
+		if volume.Ephemeral != nil && volume.Ephemeral.VolumeClaimTemplate != nil && volume.Ephemeral.VolumeClaimTemplate.Spec.Resources.Claims != nil {
+			t.Errorf("volume #%d: Resources.Claim should be nil", i)
+		}
+	}
+}