Merge branch '60303-replace-sidekiq-mtail-metrics' into 'master'

Adds sidekiq worker label for ruby metrics

Closes #60303

See merge request gitlab-org/gitlab-ce!29215

changelogs/unreleased/60303-replace-sidekiq-mtail-metrics.yml

+---
+title: Replaces sidekiq mtail metrics with ruby instrumentation metrics
+merge_request: 29215
+author:
+type: changed

config/initializers/7_prometheus_metrics.rb

@@ -19,12 +19,6 @@ Gitlab::Application.configure do |config|
   config.middleware.insert(1, Gitlab::Metrics::RequestsRackMiddleware)
 end
 
-Sidekiq.configure_server do |config|
-  config.on(:startup) do
-    Gitlab::Metrics::SidekiqMetricsExporter.instance.start
-  end
-end
-
 if !Rails.env.test? && Gitlab::Metrics.prometheus_metrics_enabled?
   Gitlab::Cluster::LifecycleEvents.on_worker_start do
     defined?(::Prometheus::Client.reinitialize_on_pid_change) && Prometheus::Client.reinitialize_on_pid_change

lib/gitlab/metrics/samplers/ruby_sampler.rb

@@ -77,10 +77,10 @@ module Gitlab
         end
 
         def worker_label
+          return { worker: 'sidekiq' } if Sidekiq.server?
           return {} unless defined?(Unicorn::Worker)
 
           worker_no = ::Prometheus::Client::Support::Unicorn.worker_id
-
           if worker_no
             { worker: worker_no }
           else