edge: remove rtx from recv encoding parameters
edge: remove rtx from recv encoding parameters

Edge 14942 throws errors if that field is present.

webrtc/adapter,Acidburn0zzz/adapter,Acidburn0zzz/adapter,jan-ivar/adapter,Acidburn0zzz/adapter,xdumaine/adapter,jan-ivar/adapter,xdumaine/adapter,webrtc/adapter