Merge pull request #59291 from bsalamat/fix_validation

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Remove validation failure of Pod priority when the feature is disabled

**What this PR does / why we need it**:
I learned that fields specified in the API should be silently ignored when the feature is disabled. This makes sense as downgrading a cluster would fail otherwise. This PR removes the validation logic that ensures Pod priority is not set when priority feature is disabled.

**Special notes for your reviewer**:

**Release note**:

```release-note
Pod priority can be specified ins PodSpec even when the feature is disabled, but it will be effective only when the feature is enabled.
```

/sig scheduling
ref: #57471

pkg/apis/core/validation/validation_test.go

@@ -5970,34 +5970,6 @@ func TestValidatePodSpec(t *testing.T) {
 			t.Errorf("expected failure for %q", k)
 		}
 	}
-
-	err = utilfeature.DefaultFeatureGate.Set("PodPriority=false")
-	if err != nil {
-		t.Errorf("Failed to disable feature gate for PodPriority: %v", err)
-		return
-	}
-	priority := int32(100)
-	featuregatedCases := map[string]core.PodSpec{
-		"set PriorityClassName": {
-			Volumes:           []core.Volume{{Name: "vol", VolumeSource: core.VolumeSource{EmptyDir: &core.EmptyDirVolumeSource{}}}},
-			Containers:        []core.Container{{Name: "ctr", Image: "image", ImagePullPolicy: "IfNotPresent", TerminationMessagePolicy: "File"}},
-			RestartPolicy:     core.RestartPolicyAlways,
-			DNSPolicy:         core.DNSClusterFirst,
-			PriorityClassName: "valid-name",
-		},
-		"set Priority": {
-			Volumes:       []core.Volume{{Name: "vol", VolumeSource: core.VolumeSource{EmptyDir: &core.EmptyDirVolumeSource{}}}},
-			Containers:    []core.Container{{Name: "ctr", Image: "image", ImagePullPolicy: "IfNotPresent", TerminationMessagePolicy: "File"}},
-			RestartPolicy: core.RestartPolicyAlways,
-			DNSPolicy:     core.DNSClusterFirst,
-			Priority:      &priority,
-		},
-	}
-	for k, v := range featuregatedCases {
-		if errs := ValidatePodSpec(&v, field.NewPath("field")); len(errs) == 0 {
-			t.Errorf("expected failure due to gated feature: %q", k)
-		}
-	}
 }
 
 func extendPodSpecwithTolerations(in core.PodSpec, tolerations []core.Toleration) core.PodSpec {