We're filtering the events using `Event#visible_to_user?`.
At most we're loading 100 events at once.
Pagination is also dealt with in the finder, but the resulting array
is wrapped in a `Kaminari.paginate_array` so the API's pagination
helpers keep working. We're passing the total count into that
paginatable array, which would include confidential events. But we're
not disclosing anything.
This change fixes a bug where an anonymous user was able to see the
activity related to internal projects when visiting the public profile
of a user of the GitLab instance.
