Add abstract attribute to base jobs

We now have the abstract attribute to mark jobs that should not run
directly, use this for base jobs.

Change-Id: I4dc85ad536946319ef8d3b68a40b94b702918086

zuul.d/jobs.yaml

@@ -26,6 +26,7 @@
 - job:
     name: base
     parent: null
+    abstract: true
     description: |
       The base job for OpenStack's installation of Zuul.
 
@@ -69,6 +70,7 @@
 - job:
     name: base-minimal
     parent: null
+    abstract: true
     description: |
       A subset of what the 'base' job provides: the absolute minimum considered
       required to run for any one job.
@@ -586,6 +588,7 @@
 
 - job:
     name: base-publish-static
+    abstract: true
     description: |
       Base job for jobs that publish content to static.openstack.org.
     pre-run: playbooks/sphinx/pre.yaml
@@ -928,6 +931,7 @@
 
 - job:
     name: build-wheel-mirror-base
+    abstract: true
     description: |
       Base job for building of wheel for OpenStack CI mirrors.
     pre-run: playbooks/wheel/pre.yaml
@@ -1112,6 +1116,7 @@
 
 - job:
     name: project-config-bindep-fallback
+    abstract: true
     description: |
       Check installation of binary packages for file
       jenkins/data/bindep-fallback.txt.