Make sure local users don't get notifications concerning other wikis

Currently, the HQL query that get events from the event stream does not restrict on the wiki. Which means that a local user can receive notifications from the main wiki for example.

Actually, it is currently hidden by the fact that we always check if the user has the right to see the document. But it means the database can return a lot of events from other wikis and so the performances can be bad.

My solution is simple: if the user is not a global user, only return notifications that concern the wiki of the user.