Due to a bug (#40098), legacy oneshot connections have not worked for
awhile. Connections without the turbotunnel token would cause the server
to crash. This fixes that bug by removing support altogether and simply
closes the connection.
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.
