Bug 33865: (bug 27421 follow-up) Remove leftover

Bug 33865: (bug 27421 follow-up) Remove leftover

Bug 27421 replaced the progress bar with job_progress.inc.
The code related to the old progress bar has not been removed however.

Moreover there was a JS error in the console:
"Uncaught ReferenceError: submitBackgroundJob is not defined"

Test plan:
Stage a MARC record for import
Import it
Revert the import
All should work correctly, without JS error in the console and with the
progress bar displayed nicely during the staging step.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>