Add stein branchful containers-multinode-stein

Create job definition and add it to the layout of branchful job
template.

Depends-On: https://review.openstack.org/#/c/647419

Change-Id: I0d3fb1b47e7eae843939cdc79c2eb4a65b22ac61
Story: https://tree.taiga.io/project/tripleo-ci-board/us/845

zuul.d/multinode-jobs.yaml

@@ -76,6 +76,7 @@
     name: tripleo-multinode-branchful
     check:
       jobs:
+        - tripleo-ci-centos-7-containers-multinode-stein
         - tripleo-ci-centos-7-containers-multinode-rocky
         - tripleo-ci-centos-7-containers-multinode-queens
         - tripleo-ci-centos-7-containers-multinode-pike
@@ -90,6 +91,20 @@
       playbooks:
         - multinode.yml
 
+- job:
+    name: tripleo-ci-centos-7-containers-multinode-stein
+    parent: tripleo-ci-base-multinode
+    timeout: 10800
+    voting: false
+    branches: master
+    override-checkout: 'stable/stein'
+    vars:
+      branch_override: 'stable/stein'
+      nodes: 1ctlr
+      featureset: '010'
+      playbooks:
+        - multinode.yml
+
 - job:
     name: tripleo-ci-centos-7-containers-multinode-rocky
     parent: tripleo-ci-base-multinode