Merge pull request #62497 from MrHohn/endpoint-controller-headless-ports

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>.

Fix a bug that headless service without ports fails to have endpoint created.

**What this PR does / why we need it**:
Follow up of https://github.com/kubernetes/kubernetes/pull/47250. Headless service without ports fails to have corresponding endpoint created because endpoint controller deliberately attaches a dummy endpointPort with portNum=0, which will fail API validation check. Error as below:
```
endpoints_controller.go:375] Error syncing endpoints for service "default/XXX": Endpoints "XXX" is invalid: subsets[0].ports[0].port: Invalid value: 0: must be between 1 and 65535, inclusive
```

This PR makes endpoint controller not attach the dummy endpointPort for headless service.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #55158, fixes #62440 

**Special notes for your reviewer**:
cc @xiangpengzhao 

**Release note**:

```release-note
Fix a bug that headless service without ports fails to have endpoint created.
```

pkg/controller/endpoint/endpoints_controller_test.go

@@ -753,7 +753,7 @@ func TestSyncEndpointsHeadlessService(t *testing.T) {
 		},
 		Subsets: []v1.EndpointSubset{{
 			Addresses: []v1.EndpointAddress{{IP: "1.2.3.4", NodeName: &emptyNodeName, TargetRef: &v1.ObjectReference{Kind: "Pod", Name: "pod0", Namespace: ns}}},
-			Ports:     []v1.EndpointPort{{Port: 0, Protocol: "TCP"}},
+			Ports:     []v1.EndpointPort{},
 		}},
 	})
 	endpointsHandler.ValidateRequestCount(t, 1)