Allow running jobs hourly

[jsnshrmn]

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Description

• switch from host crontab docker exec -t $(docker ps -q -f name=production_externallinks) python manage.py runcrons to using a docker swarm service running python manage.py cronloop
• switch from default cache-based cron job lock to db-based lock

Rationale

• switching cron lock providers means we no longer have to have a "dumb" shared timeout for all jobs
• it also means that we can see the active locks in django admin
• switching to a cronloop swarm service makes troubleshooting much easier

Phabricator Ticket

https://phabricator.wikimedia.org/T351860

How Has This Been Tested?

• I ran this locally and verified that the userlist job now runs hourly.

Screenshots of your changes (if appropriate):

Types of changes

What types of changes does your code introduce? Add an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)