Project authorizations are never cached if user has access to zero projects
Summary
When user has access to zero projects we never update authorized_projects_populated flag. This means that every time User#authorized_projects is called we perform the computations again.
This is caused by https://gitlab.com/gitlab-org/gitlab-ce/blob/f264ec6ee74a0263b4e5212e921c4638c25f8fcd/app/services/users/refresh_authorized_projects_service.rb#L77.
The bug was introduced in https://gitlab.com/gitlab-org/gitlab-ce/commit/f73193c328b871a9a3af803012c10d9bc1bd0904.