test student notifications when teacher deletes time slot
test student notifications when teacher deletes time slot

refs #7056

Test plan:
- this bug didn't actually exist, but there were no tests for this case
  so this adds one

Change-Id: I0f0e6756fc17f8de4a5c5efce9d94f2e254e4f23
Reviewed-on: https://gerrit.instructure.com/9337
Reviewed-by: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Tested-by: Hudson <dfb64870173313a9a7b56f814c8e3b33e268497a@instructure.com>

wrdsb/canvas-lms,antoniuslin/canvas-lms,sli7246/canvas_branch,rup/Tarrax,wrdsb/canvas-lms,redconfetti/canvas-lms,Jyaasa/canvas-lms,narigone/canvas,eCNAP/CANVAS,sfu/canvas-lms,arrivu/jigsaw-lms,arrivu/hiring-site,utkarshx/canvas-lms,va7map/canvas-lms,Unow/ins,SwinburneOnline/canvas-lms,usmschuck/canvas,narigone/canvas,landonwilkins/canvas-lms,efrj/canvas-lms,SwinburneOnline/canvas-lms,redconfetti/canvas-lms,Rvor/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,va7map/canvas-lms,arrivu/qibla-ecampus,skmezanul/canvas-lms,wye0220/shindig-canvas,HotChalk/canvas-lms,greyhwndz/canvas-lms,juoni/canvas-lms,arrivu/arrivu-lms,djbender/canvas-lms,samuels410/greatlakes-lms,nditech/red-innovadores-lms,jay3126/canvas-lms,parbros/red-innovadores-lms,snehakachroo1/LSI_replica,fronteerio/canvas-lms,HotChalk/canvas-lms,juoni/canvas-lms,icelab/canvas,Jyaasa/canvas-lms,arrivu/hiring-site,wimemx/Canvas,utkarshx/canvas-lms,rup/Tarrax,Rvor/canvas-lms,Unow/canvas-lms,wimemx/Canvas,eCNAP/CANVAS,djbender/canvas-lms,kyroskoh/canvas-lms,matematikk-mooc/canvas-lms,AndranikMarkosyan/lms,whalejasmine/canvas-lms,wye0220/shindig-canvas,samuels410/greatlakes-lms,wimemx/Canvas,merichar/canvas-lms,ShreniiNepal/shrenii_lmp,arrivu/hiring-site,grahamb/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,narigone/canvas,redconfetti/canvas-lms,arrivu/qibla-ecampus,arrivu/arrivu-lms,Unow/ins,arrivu/hoodemo,shidao-fm/canvas-lms,va7map/canvas-lms,instructure/canvas-lms,icelab/canvas,leftplusrightllc/canvas-lms,Unow/canvas-lms,shidao-fm/canvas-lms,venturehive/canvas-lms,grahamb/canvas-lms,ShreniiNepal/shrenii_lmp,samuels410/greatlakes-lms,instructure/canvas-lms,utkarshx/canvas-lms,Jyaasa/canvas-lms,arrivu/arrivu-lms,roxolan/canvas-lms,sdeleon28/canvas-lms,dgynn/canvas-lms,sli7246/canvas_branch,merichar/canvas-lms,wrdsb/canvas-lms,ShreniiNepal/shrenii_lmp,usmschuck/canvas,leftplusrightllc/canvas-lms,snehakachroo1/LSI_replica,jay3126/canvas-lms,whalejasmine/canvas-lms,skmezanul/canvas-lms,antoniuslin/canvas-lms,Unow/canvas-lms,em2/canvas-lms,greyhwndz/canvas-lms,nditech/red-innovadores-lms,arrivu/jigsaw-lms,efrj/canvas-lms,shidao-fm/canvas-lms,Jyaasa/canvas-lms,landonwilkins/canvas-lms,usmschuck/canvas,icelab/canvas,dgynn/canvas-lms,grahamb/canvas-lms,kyroskoh/canvas-lms,loganrun/pincan,Unow/ins,AndranikMarkosyan/lms,rup/Tarrax,greyhwndz/canvas-lms,jay3126/canvas-lms,arrivu/qibla-ecampus,efrj/canvas-lms,greyhwndz/canvas-lms,instructure/canvas-lms,gbleydon/canvas-lms,wrdsb/canvas-lms,tgroshon/canvas-lms,leftplusrightllc/canvas-lms,AndranikMarkosyan/lms,roxolan/canvas-lms,eCNAP/CANVAS,arrivu/hoodemo,juoni/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,va7map/canvas-lms,em2/canvas-lms,snehakachroo1/LSI_replica,kyroskoh/canvas-lms,roxolan/canvas-lms,fronteerio/canvas-lms,narigone/canvas,tgroshon/canvas-lms,sdeleon28/canvas-lms,grahamb/canvas-lms,eCNAP/CANVAS,whalejasmine/canvas-lms,landonwilkins/canvas-lms,arrivu/jigsaw-lms,parbros/red-innovadores-lms,sdeleon28/canvas-lms,HotChalk/canvas-lms,fronteerio/canvas-lms,nditech/red-innovadores-lms,utkarshx/canvas-lms,merichar/canvas-lms,SwinburneOnline/canvas-lms,nditech/red-innovadores-lms,leftplusrightllc/canvas-lms,dgynn/canvas-lms,gbleydon/canvas-lms,sli7246/canvas_branch,matematikk-mooc/canvas-lms,HotChalk/canvas-lms,venturehive/canvas-lms,efrj/canvas-lms,snehakachroo1/LSI_replica,Rvor/canvas-lms,sfu/canvas-lms,grahamb/canvas-lms,antoniuslin/canvas-lms,whalejasmine/canvas-lms,ankithbti/canvas_lms,parbros/red-innovadores-lms,juoni/canvas-lms,sfu/canvas-lms,fronteerio/canvas-lms,kyroskoh/canvas-lms,roxolan/canvas-lms,shidao-fm/canvas-lms,usmschuck/canvas,dgynn/canvas-lms,jay3126/canvas-lms,em2/canvas-lms,AndranikMarkosyan/lms,wye0220/shindig-canvas,matematikk-mooc/canvas-lms,sfu/canvas-lms,arrivu/hoodemo,tgroshon/canvas-lms,sdeleon28/canvas-lms,skmezanul/canvas-lms,SwinburneOnline/canvas-lms,tgroshon/canvas-lms,Rvor/canvas-lms,loganrun/pincan,instructure/canvas-lms,skmezanul/canvas-lms,djbender/canvas-lms,landonwilkins/canvas-lms,samuels410/greatlakes-lms,loganrun/pincan,redconfetti/canvas-lms,gbleydon/canvas-lms,djbender/canvas-lms,instructure/canvas-lms,antoniuslin/canvas-lms,ankithbti/canvas_lms,ankithbti/canvas_lms,matematikk-mooc/canvas-lms,instructure/canvas-lms,ShreniiNepal/shrenii_lmp