Add worker queue definition

This adds the required worker queue definition for sidekiq, with its
configuration and generated defintion.

app/workers/issue_rebalancing_worker.rb

@@ -3,11 +3,15 @@
 class IssueRebalancingWorker # rubocop:disable Scalability/IdempotentWorker
   include ApplicationWorker
 
+  idempotent!
+  urgency :low
+  feature_category :issue_tracking
+
   def perform(issue_id)
     issue = Issue.find(issue_id)
 
     rebalance(issue)
-  rescue ActiveRecord::RecordNotFound => e
+  rescue ActiveRecord::RecordNotFound, IssueRebalancingService::TooManyIssues, RelativePositioning::NoSpaceLeft => e
     Sidekiq.logger.warn(e)
   end
 

config/sidekiq_queues.yml

@@ -138,6 +138,8 @@
   - 2
 - - irker
   - 1
+- - issue_rebalancing
+  - 1
 - - jira_connect
   - 1
 - - jira_importer