spec: fix conversations_new_spec for g/35091

Change-Id: I4c069758c855135082013e4c1a83ef1d97aca40f
Reviewed-on: https://gerrit.instructure.com/35657
Reviewed-by: Bryan Madsen <bryan@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
QA-Review: Bryan Madsen <bryan@instructure.com>
Tested-by: Bryan Madsen <bryan@instructure.com>