Drop FF load_balancing_for_pipeline_notification_worker

Changelog: removed

app/workers/pipeline_notification_worker.rb

@@ -8,7 +8,7 @@ class PipelineNotificationWorker # rubocop:disable Scalability/IdempotentWorker
 
   urgency :high
   worker_resource_boundary :cpu
-  data_consistency :delayed, feature_flag: :load_balancing_for_pipeline_notification_worker
+  data_consistency :delayed
 
   def perform(pipeline_id, args = {})
     case args

config/feature_flags/development/load_balancing_for_pipeline_notification_worker.yml

----
-name: load_balancing_for_pipeline_notification_worker
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/66459
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/336517
-milestone: '14.2'
-type: development
-group: group::pipeline authoring
-default_enabled: false
-

spec/workers/pipeline_notification_worker_spec.rb

@@ -23,7 +23,6 @@ RSpec.describe PipelineNotificationWorker, :mailer do
 
     it_behaves_like 'worker with data consistency',
       described_class,
-      feature_flag: :load_balancing_for_pipeline_notification_worker,
       data_consistency: :delayed
   end
 end