Update image on AWS HA page
In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/11446 we modified the text to recommend against using EFS with GitLab, however the giant image at the top of the page still shows EFS. I had a customer yesterday who set his environment up with EFS despite looking at this page, because he saw it in the image. Even though he read the commentary further down the page. I think we need to get an updated image on this page.