fix Submission#attachments
fix Submission#attachments

fixes CNVS-25271
fixes CNVS-25273

Test plan:
  * enable crocodoc
  * disable canvadocs
  * submit a crocodocable assignment
  * enable canvadocs (with annotations)
  * re-submit the assignment (with an attachment)
  * in speedgrader, you should get a crocodoc preview through canvadocs
  * there should be no warnings about crocodoc still processing the doc

Change-Id: Id000354bf4c297a8cd7059b3cd220cb30ff532d7
Reviewed-on: https://gerrit.instructure.com/67742
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Tested-by: Jenkins
QA-Review: Amber Taniuchi <ef4bfd1e6d278f6bc7d4a478f02be2cb9581a0a5@instructure.com>
Product-Review: Josh Simpson <bfb4987b134a00f73d881fff5113b1d5fa1876bc@instructure.com>

dgynn/canvas-lms,djbender/canvas-lms,fronteerio/canvas-lms,redconfetti/canvas-lms,sfu/canvas-lms,roxolan/canvas-lms,matematikk-mooc/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,sfu/canvas-lms,HotChalk/canvas-lms,fronteerio/canvas-lms,matematikk-mooc/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,redconfetti/canvas-lms,djbender/canvas-lms,matematikk-mooc/canvas-lms,sfu/canvas-lms,dgynn/canvas-lms,SwinburneOnline/canvas-lms,fronteerio/canvas-lms,HotChalk/canvas-lms,instructure/canvas-lms,narigone/canvas,snehakachroo1/LSI_replica,narigone/canvas,roxolan/canvas-lms,snehakachroo1/LSI_replica,fronteerio/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,grahamb/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,dgynn/canvas-lms,narigone/canvas,sfu/canvas-lms,instructure/canvas-lms,venturehive/canvas-lms,redconfetti/canvas-lms,sfu/canvas-lms,roxolan/canvas-lms,narigone/canvas,sfu/canvas-lms,grahamb/canvas-lms,matematikk-mooc/canvas-lms,redconfetti/canvas-lms,HotChalk/canvas-lms,venturehive/canvas-lms,snehakachroo1/LSI_replica,instructure/canvas-lms,djbender/canvas-lms,snehakachroo1/LSI_replica,instructure/canvas-lms,HotChalk/canvas-lms,djbender/canvas-lms,dgynn/canvas-lms,SwinburneOnline/canvas-lms,roxolan/canvas-lms,grahamb/canvas-lms