skip intermediate join table for counts report query

Change-Id: I60350b953815a53d287797c12ed2fe2886132e88
Reviewed-on: https://gerrit.instructure.com/30295
Reviewed-by: Rob Orton <rob@instructure.com>
Reviewed-by: Hubert depesz Lubaczewski <hlubaczewski@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

lib/reporting/counts_report.rb

@@ -67,7 +67,8 @@ class CountsReport
           else
             timespan = Setting.get('recently_logged_in_timespan', 30.days.to_s).to_i.seconds
             enrollment_scope = Enrollment.active.not_fake.
-              joins(:user => :active_pseudonyms).
+              joins("INNER JOIN pseudonyms ON enrollments.user_id=pseudonyms.user_id").
+              where(pseudonyms: { workflow_state: 'active'}).
               where("course_id IN (?) AND pseudonyms.last_request_at>?", course_ids, timespan.ago)
 
             data[:teachers] = enrollment_scope.where(:type => 'TeacherEnrollment').count(:user_id, :distinct => true)