Automatically subscribe workers to the per-task queues
That only works for actual workers (the celeryd_after_setup signal isn't sent by the test fixture), so keep the workaround in the fixture
Depends on !23 (closed)
Test Plan
- tox
- Run a worker with a custom config: the task queues get subscribed.
- Run a worker with no custom config and -I swh.loader.debian.tasks,swh.loader.git.tasks: the task queues get subscribed as well.
Migrated from D852 (view on Phabricator)