Avoid parse remote addr twice in processRequestCommand when call RpcHook

[lifepuzzlefun]

NettyRemotingAbstract#processRequestCommand will call RpcHook before and after process request.
origin code parse twice remote addr. i think we can use local variable to save string generate by parseChannelRemoteAddr

[panzhi33]

are you interested in contributing a fix to this?

[RongtongJin]

Merged