spec: fix external_tools_spec for draft state

refs #CNVS-15563

Change-Id: I9be4fb4bc5541d85f078a21da2106da9838c693c
Reviewed-on: https://gerrit.instructure.com/43347
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>