Motivation:
At the moment we add a handler which will respond with 403 forbidden if a websocket handshake is in progress (and after). This makes not much sense as it is unexpected to have a remote peer to send another http request when the handshake was started. In this case it is much better to let the websocket decoder bail out.
Modifications:
Remove usage of forbiddenHttpRequestResponder
Result:
Fixes https://github.com/netty/netty/issues/9913