webrtcbin: Remove queue after rtpfunnel

The original BUNDLE support commit placed a queue after the rtpfunnel that combines streams, but I don't see a good reason for it. It has default settings, so if network output is slow might accidentally store up to 1 second of pending data, increasing latency.

Remove it in favour of doing any necessary buffering before webrtcbin. If it turns out that there is a reason for it to exist, the limits should probably be configurable and small.