Extract EE specific files/lines for app/views/admin/application_settings

We have the following files containing EE specific code. We should move them to ee/

• app/views/admin/application_settings/_account_and_limit.html.haml
• app/views/admin/application_settings/_ci_cd.html.haml
• app/views/admin/application_settings/_email.html.haml
• app/views/admin/application_settings/_help_page.html.haml
• app/views/admin/application_settings/_repository_mirrors_form.html.haml
• app/views/admin/application_settings/_visibility_and_access.html.haml

If we use render_if_exists from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/5767 it would be quite simple to do.

Not sure about this one though:

-      = _('Configure push mirrors.')
+      = _('Configure push and pull mirrors.')

Was pull mirrors EE only feature?