fix icon on "Delete Rubric" button with the rubrics page
fix icon on "Delete Rubric" button with the rubrics page

Fixes: CNVS-37864

test plan:
- as a teacher/admin
- navigate to a course with an existing outcome
- within the outcomes table select the (...) Manage Rubrics btn
- if there isn't an existing rubric... create one, otherwise
  select from the list of rubrics
- the "Delete Rubric" button in the right-hand side should now
  have an icon-trash vs an "X"
- example of new view: https://screencast.com/t/qavj72Cy

Change-Id: Ia97c50f93ace4631bb0203ec4749dc8aaf654a9a
Reviewed-on: https://gerrit.instructure.com/117144
Tested-by: Jenkins
Reviewed-by: Chris Hart <b82b40b84a2f06957ec9caf1768340bd6b929cc4@instructure.com>
QA-Review: Dan Sasaki <ae19fabf7fe19dff310008c9b6a4d2ec84d311d8@instructure.com>
Product-Review: Kyle Follett <3f0dcef4ea7407b413e459a87705152d37b86e63@instructure.com>

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