fix(proxy): up/down traffic stats being mixed up
We look from the client's perspective. When it sends data to the server, we say it's outbound traffic. When the server sends data to the client, it's inbound traffic:
- https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/blob/7db2568448fed6d883b33db11e3a497c69f1748f/proxy/lib/snowflake.go#L414
- https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/blob/7db2568448fed6d883b33db11e3a497c69f1748f/proxy/lib/webrtcconn.go#L78
But in the log messages they are mixed up, which results in "up" traffic being usually thicker than "down":
