Prefix package upload folder by /packaging-deb

Currently, the upload is done directly at:
http://tarballs.openstack.org/openstack-pkg-tools/

That's not what we need: we don't want to have
http://tarballs.openstack.org/nova/ full of debian packages,
so it's best to have:
http://tarballs.openstack.org/packaging-deb/nova/
for example.

So, this patch is a trivial fix to the deb-pkgs publisher
macro that adds the prefix.

Change-Id: I6df97318dd995e6f562513ad917f93c13b7b2293

jenkins/jobs/macros.yaml

@@ -894,7 +894,7 @@
       - scp:
           site: 'tarballs.openstack.org'
           files:
-            - target: 'tarballs/{project}/'
+            - target: 'tarballs/packaging-deb/{project}/'
               source: 'uploads/**'
               keep-hierarchy: true