spec: fragile content_migration spec pending

Change-Id: Ibd6070411e10d00e278c79449e06a8aae717f4d7
Reviewed-on: https://gerrit.instructure.com/40100
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Bryan Madsen <bryan@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
QA-Review: Bryan Madsen <bryan@instructure.com>