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>