bug: When changing islands in archipelago, seems peer are not cleared correctly

[pablitar]

Steps to reproduce in peer.decentraland.zone, with an archipelago realm:

1. Connect with a friend (or an incognito browser 🥲)
2. Player A should start running away
3. Once the island changes, Player B should start chasing Player A
4. Player B should see a "phantom" of Player A in the last reported position it received

It seems that we are not clearing some peer structures when changing islands. We should review that when changing islands, peers that are not in the same island are removed from every structure.