spec: add specs around kaltura partner_data for file uploads

these specs express the current behavior, which needs to be fixed to
handle sharding

Change-Id: I0c2d11e5862a02f1d4d808f4aa665288accca142
Reviewed-on: https://gerrit.instructure.com/39412
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>
Product-Review: Paul Hinze <paulh@instructure.com>
QA-Review: Paul Hinze <paulh@instructure.com>