This should increase the maximum amount of inflight data and hopefully
the performance of Snowflake, especially for clients geographically
distant from proxies and the server.
This fixes a stats collection bug where we were converting client
addresses between a string and net.Addr using the clientAddr function
multiple times, resulting in an empty string for all addresses.
Introduce a waitgroup and done channel to ensure that both the read and
write gorouting for turbotunnel connections terminate when the
connection is closed.
