loadbalancer: fix unit tests

- fix horizon binding port (with _real trick)
- add horizon unit tests for backward compatibility and also new model
- add openstack ssl binding unit tests
- fix galera binding (do not use the binding class): for now, let's use
  haproxy puppet class, and maybe later we will adapt binding class to
  support galera_ip parameter.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>