Use the celery scoring backend
Use the celery scoring backend

This is closer to the production setup, and works around a bug with signal()
vs. the standalone scorer.

Bug: T159105
Change-Id: Ic6872785184f1efe514f3b31aaf2dd4989e15a28

wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant