spec: fix threaded discussions spec on sauce labs
spec: fix threaded discussions spec on sauce labs

refs: CQA-169

Change-Id: Ib871e3edcd68ad69f044ae24fe45889cda2d389b
Reviewed-on: https://gerrit.instructure.com/185285
Tested-by: Jenkins
Reviewed-by: Robert Lamb <bf934bf7cdbebe5899399a138c0cb75c4d783999@instructure.com>
QA-Review: Robert Lamb <bf934bf7cdbebe5899399a138c0cb75c4d783999@instructure.com>
Product-Review: Robert Lamb <bf934bf7cdbebe5899399a138c0cb75c4d783999@instructure.com>

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