Certmonger: Only notify haproxy class if it's defined
Certmonger: Only notify haproxy class if it's defined

The haproxy certmonger resource (which requests the HAProxy certs)
expected the haproxy puppet manifests to run alongside if we're using a
local CA. This is no longer the case in containerized environments, e.g.
the containerized undercloud. This makes that optional.

Change-Id: I2764ca1674dcd5ecd7886233bb5e9795ee697be3

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo