zuul: remove tripleo jobs

The tripleo jobs decided unilaterally, and without even trying
to discuss it, to remove sahara from scenario003.

Baffling to say the least.

Change-Id: I03e297296e9dcf197f12bc1516f7e1b93ef367b7
(cherry picked from commit f12022f22b)

.zuul.yaml

@@ -17,7 +17,6 @@
         - openstack-tox-cover:
             voting: false
         - sahara-grenade
-        - sahara-tripleo-ci-centos-7-scenario003-standalone
         - sahara-openstack-ansible-functional
     gate:
       queue: sahara
@@ -27,7 +26,6 @@
         - sahara-tests-tempest
         - sahara-tests-tempest-v2
         - sahara-grenade
-        - sahara-tripleo-ci-centos-7-scenario003-standalone
         - sahara-openstack-ansible-functional
     experimental:
       jobs: