Avoid storing IP addresses in memory at the broker
In order to get unique IP counts for our 24 hour broker metrics, we [store the IP addresses}(https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/blob/cc644134ad10c245ed12368b2d426ca09fca8154/broker/metrics.go#L146) of proxies and clients in memory. This is slightly better than logging it and storing it on disk, but could easily be made safer. This is only used for proxy metrics at the moment. All client metrics are poll based and do not perform unique IP counts. This work would be a prerequisite for that.
We can take a look at what we did for #34075 (closed). We need to be careful about naively hashing these addresses given the small space of valid IP addresses.