Keep scheduler jobs unique until they're done (#8287)

app/workers/scheduler/doorkeeper_cleanup_scheduler.rb

@@ -3,6 +3,8 @@
 class Scheduler::DoorkeeperCleanupScheduler
   include Sidekiq::Worker
 
+  sidekiq_options unique: :until_executed
+
   def perform
     Doorkeeper::AccessToken.where('revoked_at IS NOT NULL').where('revoked_at < NOW()').delete_all
     Doorkeeper::AccessGrant.where('revoked_at IS NOT NULL').where('revoked_at < NOW()').delete_all