Motivation:
#7269 removed an unnecessary instanciation for verifying WebSocket
handshake status code.
But it uses a hardcoded status code value for 101 instead of using the
intended `HttpResponseStatus#SWITCHING_PROTOCOLS` constant.
Modidication:
Compare actual `HttpResponseStatus` against predefined constant. Note
that `HttpResponseStatus#equals` is implemented in respect with the RFC
(only honor code, not text) so it’s intended to be used this way.
Result:
Cleaner code, use intended constant instead of hard coded value.