Add Sidekiq queueing application SLIs

What does this MR do and why?

Part of gitlab-com/gl-infra/scalability#2305 (closed)

This is similar to when we added Sidekiq execution application SLIs at !116827 (merged)

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Add Sidekiq queueing application SLIs

Similar to Sidekiq execution application SLIs, we're adding Sidekiq queueing application SLIs which eventually replaces the sidekiq_jobs_queue_duration_seconds histogram metric.

Changelog: added

How to set up and validate locally

1. Make sure production.monitoring.sidekiq_exporter.enabled is true

2. Enable feature flag Feature.enable(:sidekiq_queueing_application_slis)

3. Restart Sidekiq

   $ gdk restart rails-background-jobs
   ok: down: /Users/gregoriusmarco/Documents/workspace/gdk-10-22/services/rails-background-jobs: 0s
   ok: run: /Users/gregoriusmarco/Documents/workspace/gdk-10-22/services/rails-background-jobs: (pid 8532) 1s, normally down

4. Check that the metrics are initialized

   $ curl gdk.test:3807/metrics | rg gitlab_sli_sidekiq_queueing_apdex
   ...

5. Run a job in Rails console Chaos::SleepWorker.perform_async(1)

6. Check that the counter is incremented properly

   $ curl -s gdk.test:3807/metrics | rg gitlab_sli_sidekiq_queueing_apdex | rg Chaos::SleepWorker
   gitlab_sli_sidekiq_queueing_apdex_success_total{feature_category="not_owned",urgency="low",worker="Chaos::SleepWorker"} 1
   gitlab_sli_sidekiq_queueing_apdex_total{feature_category="not_owned",urgency="low",worker="Chaos::SleepWorker"} 1

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.