eliminate an N+1 in missing_policy_applicator
eliminate an N+1 in missing_policy_applicator

test plan:
 - specs pass

Change-Id: I1a116700ea957c4f57daec101e01c1419e623ff1
Reviewed-on: https://gerrit.instructure.com/209051
Reviewed-by: Adrian Packel <9c6a39807293376f29cba17542b4cb1b663ecc4a@instructure.com>
Tested-by: Jenkins
QA-Review: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>
Product-Review: Keith Garner <a1a80143a840c140f31c3495ebbd9ec906e09fed@instructure.com>

sfu/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms