Register Sidekiq queues only from routing rules

What does this MR do and why?

Register Sidekiq queues only from routing rules

Also clean up other queues that are outside routing rules. Most instances would have hundreds of unused queues back when we were still running queues per worker.

Changelog: changed

For #415298

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

How to set up and validate locally

With empty routing rules

1. Ensure sidekiq.routing_rules is empty in gitlab.yml

2. Restart sidekiq gdk restart rails-background-jobs

3. Check Rails console

   [8] pry(main)> Sidekiq::Queue.all.map(&:name)
   => ["default", "mailers"]

4. Or check queues set in Redis

❯ gdk redis-cli -n 1 smembers queues
1) "default"
2) "mailers"

With a custom routing rules

1. Paste this in gitlab.yml

     sidekiq:
       log_format: json # (default is also supported)
       routing_rules:
         - ["urgency=high", "urgent"]
         - ["urgency=low", "not-urgent"]
         - ["*", "default"]

2. Restart gdk restart rails-background-jobs

3. Check queues

   ❯ gdk redis-cli -n 1 smembers queues
   1) "urgent"
   2) "not-urgent"
   3) "default"
   4) "mailers"