In cases when internal and external haproxy frontends should use
different, pre-generated certificates, it's not possible to define them
with haproxy_user_ssl_cert because it accepts only one certificate.
In this case, certificates can be placed manually in pki/ directory.
Unfortunately, with current logic, certificates creation with PKI role
is disabled only when haproxy_user_ssl_cert is defined.
Possibility of explicitly disabling certificates generation will be
really useful.
Depends-On: https://review.opendev.org/c/openstack/openstack-ansible-os_nova/+/915320/
Change-Id: I4eed4d797160b885d5b7187e6106e6ee0073722f
ed8eeba8d3