Haproxy was renamed in [1].

[1] https://review.opendev.org/c/openstack/kolla-ansible/+/770618

Change-Id: Ib2d7f0774fede570a8c4c315d83afd420c31da0b

For now role haproxy is maintaining haproxy
and keepalived. In follow-up changes there is also
proxysql added.

This patch is *only* renaming/moving stuff to more
prominent role loadbalancer, and moving also specific
templates to subdirectory.

This was done only to better diff in follow-up
changes.

Change-Id: I1d39d5bcaefc4016983bf267a2736b742cc3a555