[China] Blocking Hetzner wholesale

The China vantage point has been returning that Hetzner bridges are blocked as soon as they are deployed, while bridges deployed on OVH do not have this issue. I assume this means they are doing something to the entire Hetzner IP range. We currently only supply IPv4 bridgelines so I don't know if this affects IPv6, though we do have IPv6 on the Hetzner bridges. In discussion on IRC it was mentioned that this could be throttling rather than outright blocking and our vantage point has too high standards to wait for the bootstrap to complete. To avoid deploying bridges that will just be immediately rotated I have disabled deployments to Hetzner but I can deploy one for testing if required.