Use <project>_install_type instead of kolla_install_type
to set python_path. For example, general kolla_install_type
is 'binary', but user wants to deploy Horizon from 'source'.
Horizon templates still use python_path=/usr/share/openstack-dashboard,
it is wrong.

Change-Id: Ide6a24e17b1f8ab6506aa5e53f70693706830418