"Use an image from elsewhere on the web" test failing

Currently, the "Use an image from elsewhere on the web" test in wysiwyg_media.feature is failing. It's because the image URL we're using is for an image that's gone now! It's probably due to files to old logos getting cleaned up on Drupal.org after the D8 launch.

Let's change the URL to something that works, like: https://www.drupal.org/files/drupal_logo-blue.png