Replace authenticated default login image

When you set hst:authenticated = true, you get a default login page. The image on this page is still a Hippo image. In fact, it is at least 8 years old, but probably older. The history doesn't go back further.

The image is:
/hippo-site-toolkit/components/security/src/main/resources/META-INF/hst/security/skin/images/loginhead.png

This should be replaced by a bloomreach logo