fix collapsed module title css

test plan:
* with draft state enabled, create a module
* collapse the module
* confirm that the title is not hidden

fixes #CNVS-12607

Change-Id: I06c6c884b3c5756d2a1f84b55df9dcedb784404d
Reviewed-on: https://gerrit.instructure.com/34386
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Nathan Rogowski <nathan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>