Add new base for containers-build and periodic without files:

As tracked in [1] in order to use the upstream as base in the
periodic containers build job, we need the base to *not* have any
files: defined otherwise zuul refuses to run it. There is more
info on this bug at [2]

This adds new tripleo-build-containers-base in the base.yaml file
and the existing job then parents onto that see [3]

[1] https://tree.taiga.io/project/tripleo-ci-board/task/712
[2] https://storyboard.openstack.org/#!/story/2005040
[3] https://review.rdoproject.org/r/#/c/18896/
Change-Id: I7520b19eb85069e5d75c000f73cbc3499fedeec7

zuul.d/base.yaml

@@ -155,3 +155,26 @@
       tags:
         - build
         - standalone
+
+# Please do not add files: to tripleo-build-containers-base otherwise the periodic job wont run
+# See https://storyboard.openstack.org/#!/story/2005040
+- job:
+    name: tripleo-build-containers-base
+    abstract: true
+    description: |
+        Base abstract job for standalone TripleO CI build-containers jobs
+    parent: tripleo-ci-base-singlenode
+    pre-run:
+      - playbooks/tripleo-buildcontainers/pre.yaml
+    run: playbooks/tripleo-buildcontainers/run.yaml
+    post-run: playbooks/tripleo-buildcontainers/post.yaml
+    timeout: 7200
+    voting: false
+    required-projects:
+      - git.openstack.org/openstack/ansible-role-container-registry
+      - git.openstack.org/openstack/kolla
+      - git.openstack.org/openstack/python-tripleoclient
+      - git.openstack.org/openstack/requirements
+      - git.openstack.org/openstack/tripleo-common
+      - git.openstack.org/openstack/tripleo-repos
+

zuul.d/build-containers.yaml

@@ -15,28 +15,18 @@
 
 - job:
     name: tripleo-build-containers-centos-7
-    parent: tripleo-ci-base-singlenode
-    pre-run:
-      - playbooks/tripleo-buildcontainers/pre.yaml
-    run: playbooks/tripleo-buildcontainers/run.yaml
-    post-run: playbooks/tripleo-buildcontainers/post.yaml
-    timeout: 7200
+    parent: tripleo-build-containers-base
     nodeset: single-centos-7-node
     voting: true
-    required-projects:
-      - git.openstack.org/openstack/ansible-role-container-registry
-      - git.openstack.org/openstack/kolla
-      - git.openstack.org/openstack/python-tripleoclient
-      - git.openstack.org/openstack/requirements
-      - git.openstack.org/openstack/tripleo-common
-      - git.openstack.org/openstack/tripleo-repos
     irrelevant-files:
       - ^.*\.rst$
       - ^releasenotes/.*$
     files:
       # tripleo-ci
       - ^playbooks/tripleo-buildcontainers/.*$
-      - zuul.d/build-containers.yaml
+      - zuul.d/base.yaml
+      - zuul.d/nodesets.yaml
+      - roles/tripleo-repos/.*
       # tripleo-common
       - ^container-images/.*$
       - ^tripleo_common/image/.*$