Merge branch 'enable-licenses-app-default' into 'master'

Enable licenses_app feature flag by default

See merge request gitlab-org/gitlab-ee!11095

ee/app/views/admin/licenses/show.html.haml

 - page_title "License"
 
-- if Feature.enabled?(:licenses_app)
+- if Feature.enabled?(:licenses_app, default_enabled: true)
   #instance-license-mount-element{ license_app_data }
 - else
   %h3.page-title