Exclude pipeline config items for openstack-dev/ci-sandbox
Exclude pipeline config items for openstack-dev/ci-sandbox

We want to experiment with storing 3pci pipelines on git.o.o and having
downstream zuul's load it. However, to test this we first need to tell
zuul.o.o not to load pipeline configurations from
openstack-dev/ci-sandbox.

Change-Id: Ib92b92e9dff67b083947f8de89549a88dbda55ce
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

openstack-infra/project-config,openstack-infra/project-config