Show WG providers on Leaderboard too

[zolia]

group traffic by ProviderID

[tadaskay]

Discussed with @zolia and @AndriusMyst:
As there are no leaderboard nodes that exclusively run wireguard service, let's simply show only openvpn for now. Otherwise, we would need to pivot table because not all stats can be summed up (e.g. availability, unique users).
What's needed to be done here is to eliminate duplicate entries in the leaderboard.