Bring back the relays-by-country graph
Aggregating data for the relays-by-country graph has become prohibitively expensive. It keeps the server busy for 2 hours every day, affecting more important tasks like downloading descriptors. That's why I disabled this aggregation step on February 1 to the effect that relays-by-country graphs are still available but won't receive new data. The problem is the PostgreSQL-based IP-to-country lookup. I should look into making this lookup much, much faster. Creating this ticket so I don't forget.