fix accessibility issue with question groups

fixes CNVS-8252
This commit addresses a problem with screenreader and keyboard
navigation in quiz editing.  When navigating to a question group while
editing a quiz, when you tried to collapse or expand said question
group, the screenreader and browser lost focus due to the element being
hidden during the click event, which ended up causing bizarre errors as
the screenreader/browser focused on other elements.

Test Plan (See CNVS-8252 for Amber's screencast on the issue)
1. Edit a quiz that contains a question group in Safari or Chrome
2. Turn on Voice Over
3. Expand and collapse the question group using keyboard/voice over
navigation.
- The question group should expand and collapse correctly with no
  unwanted side effects.

Change-Id: Ied2bd94bb77a2a9e89589404654836ee8d589188
Reviewed-on: https://gerrit.instructure.com/30639
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
QA-Review: Myller de Araujo <myller@instructure.com>
Product-Review: Josh Simpson <jsimpson@instructure.com>