stop needlessly re-querying CourseSection overrides
stop needlessly re-querying CourseSection overrides

refs CNVS-6747

Test plan:
  make sure teachers still get the correct due date when an assignment
  has course section overrides and a default due date

Change-Id: I6ad9f99bc4558c7f1d6a48c93fbd13426d2fe409
Reviewed-on: https://gerrit.instructure.com/22531
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
QA-Review: Amber Taniuchi <ef4bfd1e6d278f6bc7d4a478f02be2cb9581a0a5@instructure.com>
Product-Review: Cameron Matheson <1d572acbfa68c7c6e541c7b840d6b622e5c0dc91@instructure.com>

usmschuck/canvas,wrdsb/canvas-lms,arrivu/arrivu-lms,greyhwndz/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,jay3126/canvas-lms,wimemx/Canvas,djbender/canvas-lms,usmschuck/canvas,greyhwndz/canvas-lms,venturehive/canvas-lms,juoni/canvas-lms,roxolan/canvas-lms,eCNAP/CANVAS,sdeleon28/canvas-lms,instructure/canvas-lms,snehakachroo1/LSI_replica,leftplusrightllc/canvas-lms,utkarshx/canvas-lms,sdeleon28/canvas-lms,samuels410/greatlakes-lms,gbleydon/canvas-lms,gbleydon/canvas-lms,dgynn/canvas-lms,jay3126/canvas-lms,fronteerio/canvas-lms,antoniuslin/canvas-lms,wimemx/Canvas,kyroskoh/canvas-lms,juoni/canvas-lms,efrj/canvas-lms,kyroskoh/canvas-lms,grahamb/canvas-lms,redconfetti/canvas-lms,fronteerio/canvas-lms,Rvor/canvas-lms,wrdsb/canvas-lms,redconfetti/canvas-lms,snehakachroo1/LSI_replica,arrivu/hoodemo,greyhwndz/canvas-lms,roxolan/canvas-lms,AndranikMarkosyan/lms,HotChalk/canvas-lms,HotChalk/canvas-lms,redconfetti/canvas-lms,Jyaasa/canvas-lms,SwinburneOnline/canvas-lms,narigone/canvas,instructure/canvas-lms,dgynn/canvas-lms,wimemx/Canvas,arrivu/hoodemo,HotChalk/canvas-lms,dgynn/canvas-lms,djbender/canvas-lms,arrivu/arrivu-lms,narigone/canvas,sdeleon28/canvas-lms,shidao-fm/canvas-lms,landonwilkins/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,va7map/canvas-lms,landonwilkins/canvas-lms,wrdsb/canvas-lms,fronteerio/canvas-lms,arrivu/qibla-ecampus,Jyaasa/canvas-lms,instructure/canvas-lms,efrj/canvas-lms,roxolan/canvas-lms,SwinburneOnline/canvas-lms,narigone/canvas,samuels410/greatlakes-lms,Rvor/canvas-lms,tgroshon/canvas-lms,wye0220/shindig-canvas,antoniuslin/canvas-lms,ShreniiNepal/shrenii_lmp,loganrun/pincan,greyhwndz/canvas-lms,va7map/canvas-lms,shidao-fm/canvas-lms,skmezanul/canvas-lms,eCNAP/CANVAS,arrivu/qibla-ecampus,ShreniiNepal/shrenii_lmp,sfu/canvas-lms,wye0220/shindig-canvas,redconfetti/canvas-lms,tgroshon/canvas-lms,kyroskoh/canvas-lms,Rvor/canvas-lms,jay3126/canvas-lms,eCNAP/CANVAS,arrivu/jigsaw-lms,sfu/canvas-lms,loganrun/pincan,SwinburneOnline/canvas-lms,skmezanul/canvas-lms,antoniuslin/canvas-lms,Unow/canvas-lms,utkarshx/canvas-lms,grahamb/canvas-lms,leftplusrightllc/canvas-lms,merichar/canvas-lms,samuels410/greatlakes-lms,landonwilkins/canvas-lms,matematikk-mooc/canvas-lms,utkarshx/canvas-lms,leftplusrightllc/canvas-lms,shidao-fm/canvas-lms,gbleydon/canvas-lms,snehakachroo1/LSI_replica,arrivu/hoodemo,sfu/canvas-lms,AndranikMarkosyan/lms,va7map/canvas-lms,arrivu/jigsaw-lms,matematikk-mooc/canvas-lms,instructure/canvas-lms,fronteerio/canvas-lms,SwinburneOnline/canvas-lms,efrj/canvas-lms,tgroshon/canvas-lms,venturehive/canvas-lms,juoni/canvas-lms,snehakachroo1/LSI_replica,samuels410/greatlakes-lms,venturehive/canvas-lms,efrj/canvas-lms,wye0220/shindig-canvas,AndranikMarkosyan/lms,matematikk-mooc/canvas-lms,jay3126/canvas-lms,matematikk-mooc/canvas-lms,juoni/canvas-lms,sdeleon28/canvas-lms,wrdsb/canvas-lms,Rvor/canvas-lms,Unow/canvas-lms,sfu/canvas-lms,merichar/canvas-lms,tgroshon/canvas-lms,Unow/canvas-lms,usmschuck/canvas,Jyaasa/canvas-lms,narigone/canvas,ShreniiNepal/shrenii_lmp,eCNAP/CANVAS,whalejasmine/canvas-lms,roxolan/canvas-lms,merichar/canvas-lms,grahamb/canvas-lms,whalejasmine/canvas-lms,arrivu/jigsaw-lms,skmezanul/canvas-lms,skmezanul/canvas-lms,arrivu/arrivu-lms,dgynn/canvas-lms,sfu/canvas-lms,kyroskoh/canvas-lms,HotChalk/canvas-lms,leftplusrightllc/canvas-lms,utkarshx/canvas-lms,instructure/canvas-lms,whalejasmine/canvas-lms,arrivu/qibla-ecampus,instructure/canvas-lms,AndranikMarkosyan/lms,Jyaasa/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,whalejasmine/canvas-lms,usmschuck/canvas,loganrun/pincan,landonwilkins/canvas-lms,va7map/canvas-lms,grahamb/canvas-lms,antoniuslin/canvas-lms,ShreniiNepal/shrenii_lmp,djbender/canvas-lms,shidao-fm/canvas-lms