Run only needed playbooks in undercloud jobs

In these jobs overcloud and upgrade playbooks also
runs which is not needed in undercloud jobs, so
let's set the playbooks var to run only the needed
playbooks.

Until https://review.opendev.org/#/c/759912/
merged it was not an issue as due to "tags" tasks
used to skip in the extra playbooks.

Depends-On: https://review.opendev.org/#/c/763519/
Change-Id: Ie1924646efd7333ce84b2a4a18c2cfc80edb7d51

zuul.d/undercloud-jobs.yaml

@@ -148,6 +148,10 @@
     branches: ^(stable/rocky).*$
     vars:
       featureset: '027'
+      playbooks:
+        - quickstart.yml
+        - multinode-undercloud.yml
+        - multinode-validate.yml
 
 - job:
     name: tripleo-ci-centos-8-undercloud-containers
@@ -156,6 +160,10 @@
     voting: true
     vars:
       featureset: '027'
+      playbooks:
+        - quickstart.yml
+        - multinode-undercloud.yml
+        - multinode-validate.yml
 
 - job:
     name: tripleo-ci-centos-7-undercloud-oooq
@@ -164,6 +172,10 @@
     branches: ^(stable/queens).*$
     vars:
       featureset: '003'
+      playbooks:
+        - quickstart.yml
+        - multinode-undercloud.yml
+        - multinode-validate.yml
 
 - job:
     name: tripleo-ci-centos-7-containerized-undercloud-upgrades