On scale environment, css logs have a flood of log messages


In my scale environment running MMS update tests, I see a flood of these  CSS log messages. 

```
Sep 17 16:09:25 ibm-edge-css-559c44dcc7-tndbz ibm-edge-css 2021/09/17 20:09:25 http: superfluous response.WriteHeader call from github.com/open-horizon/edge-sync-service/core/communications.SendErrorResponse (communicator.go:135) 
```

Would be nice to clean these up