Right now PKI role is included based of `cinder_backend_ssl`
variable, which might be globally overridable with
`openstack_service_backend_ssl`.
At the same time these certificates are used only for uWSGI, as
a backend web server, and not used anywhere else. But they will
be issued for cinder-volume and cinder-backup without any need.
Extended condition will check if we are running against a group which
also need certificates to be present.
Change-Id: I40d7fffd77ce4c6bff58279ba6bc0c5858b7452c
Signed-off-by: Dmitriy Rabotyagov <dmitriy.rabotyagov@cleura.com>