Merge pull request #48658 from CaoShuFeng/WriteHeader

Automatic merge from submit-queue (batch tested with PRs 46865, 48661, 48598, 48658, 48614)

remove extra WriteHeader function

The deleted two functions will be called later in the function
SerializeObject(). Not necessary to call them twice.

**Release note**:
```
NONE
```

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/responsewriters/writers.go

@@ -109,9 +109,6 @@ func WriteObjectNegotiated(ctx request.Context, s runtime.NegotiatedSerializer,
 		audit.LogResponseObject(ae, object, gv, s)
 	}
 
-	w.Header().Set("Content-Type", serializer.MediaType)
-	w.WriteHeader(statusCode)
-
 	encoder := s.EncoderForVersion(serializer.Serializer, gv)
 	SerializeObject(serializer.MediaType, encoder, w, req, statusCode, object)
 }