Merge branch '6591-dont-load-omniauth-if-not-enabled' into 'master'

Don't try to load omniauth if not enabled

Closes gitlab-ee#6591

See merge request gitlab-org/gitlab-ce!20132

changelogs/unreleased/6591-dont-load-omniauth-if-not-enabled.yml

+---
+title: Only load Omniauth if enabled
+merge_request: 20132
+author:
+type: fixed

config/initializers/devise.rb

@@ -219,5 +219,7 @@ Devise.setup do |config|
     end
   end
 
+  if Gitlab.config.omniauth.enabled
     Gitlab::OmniauthInitializer.new(config).execute(Gitlab.config.omniauth.providers)
+  end
 end