shorten migration names to avoid postgres index max-length.
shorten migration names to avoid postgres index max-length.

test plan:
  * on an empty postgres database, run rake db:initial_setup
    and ensure that no errors are thrown.

Change-Id: I2a4b43a7fa60bcb8e81c5c578b9dfccd19b38a28
Reviewed-on: https://gerrit.instructure.com/8625
Tested-by: Hudson <dfb64870173313a9a7b56f814c8e3b33e268497a@instructure.com>
Reviewed-by: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>

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