Stein only: Remove tripleo job

... because TripleO is moving its stable/stein to EOL.

Change-Id: Ia5a50b9e75985b8d1aa2911355f1bc9edc331dc9

.zuul.yaml

@@ -4,22 +4,4 @@
       - puppet-openstack-module-unit-jobs
       - puppet-openstack-integration-jobs-scenario002
       - puppet-openstack-beaker-jobs
-      - tripleo-puppet-undercloud
       - release-notes-jobs-python3
-    check:
-      jobs:
-        - puppet-swift-tripleo-standalone
-    gate:
-      jobs:
-        - puppet-swift-tripleo-standalone
-
-- job:
-    name: puppet-swift-tripleo-standalone
-    parent: tripleo-puppet-ci-centos-7-standalone
-    description: |
-      TripleO standalone Job running Object Storage specific Tempest tests.
-    vars:
-      featureset_override:
-        run_tempest: true
-        tempest_whitelist:
-          - 'object_storage'