Removed Heroku in-process spawning. (#1873)

config/puma.rb

@@ -8,10 +8,6 @@ workers     ENV.fetch('WEB_CONCURRENCY') { 2 }
 preload_app!
 
 on_worker_boot do
-  if ENV['HEROKU'] # Spawn the workers from Puma, to only use one dyno
-    @sidekiq_pid ||= spawn('bundle exec sidekiq -q default -q push -q pull -q mailers ')
-  end
-
   ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
 end