Set Nova auth_proto regardless of tls-proxy.

We actually want to comment out the keystone auth_proto in Nova's
api-paste.ini file regardless of the tls-proxy setting. Likewise
lets always set it in nova.conf as well.

This should fix an issue in trying to get this in:

  https://review.openstack.org/#/c/52825/

Change-Id: I1b8202aa1666cbb6ca13d2f77d50fa0175969266
Merge "Set Nova auth_proto regardless of tls-proxy."