Allow excluding sidekiq queues from execution in sidekiq-cluster

Extracted from https://gitlab.com/gitlab-com/infrastructure/issues/2197#note_34595436.

We currently allow you to run extra sidekiq processes using bin/sidekiq-cluster.

In addition to the existing arguments where a set of queues can be specified, we want an argument that can negate those, so all queues except the specified ones are picked up. That way if you run one command with queue1,queue2 and another with --negate queue1,queue2 (or whatever), you can guarantee that all queues are being picked up. We can do this by parsing sidekiq_queues.yml and then applying the operation there.

The production team are currently doing the following for this dashboard: https://performance.gitlab.net/dashboard/db/sidekiq-stats

• best-effort runs everything (regular sidekiq CLI)
• asap runs only a certain set of queues
• real-time runs only a certain set of queues

Once we add this option, we can change that to:

• best-effort runs --negate $asap_queues,$real_time_queues

(Note that to create multiple Sidekiq processes running the same sets of queues, the arguments can just be repeated: $real_time_queues $real_time_queues $real_time_queues will create three processes.)

mentioned in issue gitlab-com/infrastructure#2197 (closed)

assigned to @oswaldo

mentioned in merge request !2571 (merged)

closed via merge request !2571 (merged)

mentioned in commit d4c84653