Split jobs to multiple listeners #645
Description
At the moment we only have one listener worker that runs all the jobs. While this works, it's not ideal because certain long procedures (like evaluation) can take a long time and more import jobs (issue creation for example) can be stuck waiting for evals to finish.
Django-pgpubsub doesn't have a way to exclude certain channels, you can only specify channels to listen to with --channels otherwise it listens on all channels. We can either:
a) extend django-pgpubsub with the functionality to exclude channels
b) specify all channels for each listener manually, making sure we update the listeners when new channels are added or removed.
I think option (a) makes more sense long term.
Related to #409, but more generic.