Fix Scheduler::SubscriptionsScheduler (#2834)

* Fix Scheduler::SubscriptionsScheduler, add worker test for it

* Change production log level of Sidekiq to "warn" instead of "info"

app/workers/scheduler/subscriptions_scheduler.rb

@@ -5,9 +5,9 @@ class Scheduler::SubscriptionsScheduler
   include Sidekiq::Worker
 
   def perform
-    Rails.logger.debug 'Queueing PuSH re-subscriptions'
+    logger.info 'Queueing PuSH re-subscriptions'
 
-    expiring_accounts.pluck(:id) do |id|
+    expiring_accounts.pluck(:id).each do |id|
       Pubsubhubbub::SubscribeWorker.perform_async(id)
     end
   end