Wasted bandwidth on proxy stream timeout

[Hornwitser]

If the proxy stream created by save download request times out being established, but is then fulfilled after the timeout the full save upload is still performed to the controller and the data stream is discarded. This can lead to a lot of wasted bandwidth as happened at Eternity Cluster where a scripted save download failing caused 1 TB of traffic in 3 days. If a push to a stream is attempted after the stream has timed out it should be rejected/aborted so no bandwidth is wasted.