Fix Scheduler::SubscriptionsScheduler (#2834)

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

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

config/environments/production.rb

@@ -87,6 +87,7 @@ Rails.application.configure do
 
   config.to_prepare do
     StatsD.backend = StatsD::Instrument::Backends::NullBackend.new if ENV['STATSD_ADDR'].blank?
+    Sidekiq::Logging.logger.level = Logger::WARN
   end
 
   config.action_dispatch.default_headers = {