Increase number of tor instances from 4 to 8 on snowflake-01 bridge

Background: https://lists.torproject.org/pipermail/anti-censorship-team/2022-September/000247.html

The current 4 tor instances on the snowflake-01 bridge are saturated near 100% CPU since yesterday, due to increased usage. (Right now the bridge is at about 200 MB/s outgoing, 140 MB/s incoming.) We need to increase the number of instances.

I am a bit worried that 8 instances will permit more traffic than the hardware of the bridge will permit. I'll watch the performance and be prepared to step it back to 6.

While making the change, also increase clientIDAddrMapCapacity because snowflake-server is reporting constant "no address in clientID-to-IP map (capacity 10240)". Previous issue: #40084 (closed).

/cc @linus