Zuul: add file extension to playbook path

Zuul now supports including the file extension on the playbook path
and omitting the extension is now deprecrated.  Update references
to include the extension.

Change-Id: Ieeb6a0457993531692e63b262a44d1e8fc34cd28

.zuul.yaml

@@ -1,15 +1,15 @@
 - job:
     name: puppet-openstack-base
-    pre-run: playbooks/prepare-node-common
+    pre-run: playbooks/prepare-node-common.yaml
     vars:
-      use_puppetlabs: False
+      use_puppetlabs: false
 
 - job:
     name: puppet-openstack-integration-base
     parent: puppet-openstack-base
-    pre-run: playbooks/prepare-node-integration
-    run: playbooks/run-integration-tests
-    post-run: playbooks/upload-logs
+    pre-run: playbooks/prepare-node-integration.yaml
+    run: playbooks/run-integration-tests.yaml
+    post-run: playbooks/upload-logs.yaml
     timeout: 5400
     required-projects:
       - openstack/openstack
@@ -299,12 +299,12 @@
 - job:
     name: puppet-openstack-module-base
     parent: puppet-openstack-base
-    pre-run: playbooks/prepare-node-unit
+    pre-run: playbooks/prepare-node-unit.yaml
 
 - job:
     name: puppet-openstack-lint
     parent: puppet-openstack-module-base
-    run: playbooks/run-lint-tests
+    run: playbooks/run-lint-tests.yaml
     irrelevant-files:
       - ^.*\.md$
       - ^.*\.rst$
@@ -317,7 +317,7 @@
 - job:
     name: puppet-openstack-syntax
     parent: puppet-openstack-module-base
-    run: playbooks/run-syntax-tests
+    run: playbooks/run-syntax-tests.yaml
     irrelevant-files:
       - ^.*\.md$
       - ^.*\.rst$
@@ -343,10 +343,10 @@
 - job:
     name: puppet-openstack-module-build
     parent: puppet-openstack-module-base
-    run: playbooks/run-build-tests
+    run: playbooks/run-build-tests.yaml
     files: ^metadata.json$
     vars:
-      use_puppetlabs: True
+      use_puppetlabs: true
 
 - project-template:
     name: puppet-openstack-check-jobs