DA - fix discussion selenium spec

no test plan

Change-Id: Ibc7e41b61daf5d2389b9003ef78f7a7aa5b81e8d
Reviewed-on: https://gerrit.instructure.com/45264
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Mike Nomitch <mnomitch@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>