e2e-job-flow.sh uploads a file through the presigned URL to the real object
store, lets the real scheduler dispatch it over /ws/edge/v1 to a stand-in
gateway, which downloads it through the presigned GET and hashes it, then
reports the print running and finished. The job must pass through printing
to completed and the gateway must have received exactly the uploaded bytes.
Dispatch is on in this one, which is only safe because the stand-in is the
only gateway the backend instance under test can have; the script says so.
