Use the new Sidekiq syntax to specify queues

This syntax is compatible with the current Sidekiq version we use
(2.17.0) and it protects us against future breakage by
https://github.com/mperham/sidekiq/commit/040eda558bc64139c846c781d3de0b79603e3035

script/background_jobs

@@ -37,7 +37,7 @@ function start_no_deamonize
 
 function start_sidekiq
 {
-  bundle exec sidekiq -q post_receive,mailer,system_hook,project_web_hook,gitlab_shell,common,default -e $RAILS_ENV -P $sidekiq_pidfile $@ >> $sidekiq_logfile 2>&1
+  bundle exec sidekiq -q post_receive -q mailer -q system_hook -q project_web_hook -q gitlab_shell -q common -q default -e $RAILS_ENV -P $sidekiq_pidfile $@ >> $sidekiq_logfile 2>&1
 }
 
 function load_ok