Remove active_record.auto_explain_treshold_in_seconds, rails 4.0 deprecation

config/environments/production.rb

@@ -74,10 +74,6 @@ Gitlab::Application.configure do
   # Send deprecation notices to registered listeners
   config.active_support.deprecation = :notify
 
-  # Log the query plan for queries taking more than this (works
-  # with SQLite, MySQL, and PostgreSQL)
-  # config.active_record.auto_explain_threshold_in_seconds = 0.5
-
   config.action_mailer.delivery_method = :sendmail
   # Defaults to:
   # # config.action_mailer.sendmail_settings = {