spec: refactor wiki and tinymce selenium specs for draft state

refs #CNVS-15563

Change-Id: I4d358e0467b05383b459b6b3ccb54b25d637c85b
Reviewed-on: https://gerrit.instructure.com/43434
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>