Improve User.from_courses scope
Improve User.from_courses scope

This makes it into a single query.

WikiEducationFoundation/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,KarmaHater/WikiEduDashboard,sejalkhatri/WikiEduDashboard,alpha721/WikiEduDashboard,sejalkhatri/WikiEduDashboard,sejalkhatri/WikiEduDashboard,alpha721/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,alpha721/WikiEduDashboard,majakomel/WikiEduDashboard,KarmaHater/WikiEduDashboard,sejalkhatri/WikiEduDashboard,majakomel/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,WikiEducationFoundation/WikiEduDashboard,majakomel/WikiEduDashboard,alpha721/WikiEduDashboard,sejalkhatri/WikiEduDashboard,majakomel/WikiEduDashboard,KarmaHater/WikiEduDashboard,KarmaHater/WikiEduDashboard