Updates related to PR feedback

- Remove feature gate consideration from EndpointSlice validation
- Deprecate topology field, note that it will be removed in future
release
- Update kube-proxy to check for NodeName if feature gate is enabled
- Add comments indicating the feature gates that can be used to enable
alpha API fields
- Add comments explaining use of deprecated address type in tests

pkg/controller/endpointslice/reconciler_test.go

@@ -917,6 +917,7 @@ func TestReconcileEndpointSlicesReplaceDeprecated(t *testing.T) {
 	namespace := "test"
 
 	svc, endpointMeta := newServiceAndEndpointMeta("foo", namespace)
+	// "IP" is a deprecated address type, ensuring that it is handled properly.
 	endpointMeta.AddressType = discovery.AddressType("IP")
 
 	existingSlices := []*discovery.EndpointSlice{}