Add barbican::worker to integration testing

Adds the new barbican::worker class to the
integration testing.

Depends-On: https://review.openstack.org/#/c/598165/
Change-Id: I8bd7a134390cdec244b3a60cf895c01cf26203d0

manifests/barbican.pp

@@ -71,5 +71,6 @@ class openstack_integration::barbican {
     ssl_cert  => $::openstack_integration::params::cert_path,
     workers   => 2,
   }
+  class { '::barbican::worker': }
 
 }