Assign some CI/CD workers to pipeline default queue

app/workers/build_coverage_worker.rb

@@ -2,8 +2,6 @@ class BuildCoverageWorker
   include Sidekiq::Worker
   include PipelineQueue
-  enqueue_in group: :processing
-
   def perform(build_id)
     Ci::Build.find_by(id: build_id)&.update_coverage
   end

app/workers/pipeline_metrics_worker.rb

@@ -2,8 +2,6 @@ class PipelineMetricsWorker
   include Sidekiq::Worker
   include PipelineQueue
-  enqueue_in group: :metrics
-
   def perform(pipeline_id)
     Ci::Pipeline.find_by(id: pipeline_id).try do |pipeline|
       update_metrics_for_active_pipeline(pipeline) if pipeline.active?

app/workers/pipeline_notification_worker.rb

@@ -2,8 +2,6 @@ class PipelineNotificationWorker
   include Sidekiq::Worker
   include PipelineQueue
-  enqueue_in group: :hooks
-
   def perform(pipeline_id, recipients = nil)
     pipeline = Ci::Pipeline.find_by(id: pipeline_id)

config/sidekiq_queues.yml

@@ -28,8 +28,8 @@
   - [build, 2]
   - [pipeline, 2]
   - [pipeline_processing, 2]
+  - [pipeline_default, 2]
   - [pipeline_cache, 2]
-  - [pipeline_metrics, 2]
   - [pipeline_hooks, 2]
   - [gitlab_shell, 2]
   - [email_receiver, 2]