There is no reason to support multiple web servers as a proxy for
keystone. Nginx is missing modules to support federation. With it's
removal we simplify code and reduce maintaining efforts needed.
Change-Id: Ib3f90a72dfc8f78cf304b0f130883befdeb09220
Depends-On: https://review.opendev.org/c/openstack/openstack-ansible/+/818674