Switching playbook order of execution

Stackviz wasn't being executed when tempest have a failure, because
post-tempest exits with tempest status code. So, once tempest fails,
stackviz is not executed, not generating the report.

Change-Id: Ia87eb11bc7d0d2cae4eb76481d446a63671a99e8

roles/validate-tempest/tasks/main.yml

@@ -14,13 +14,13 @@
   tags:
     - run-tempest
 
-- include: post-tempest.yml
-  when: post_tempest|bool
-  tags:
-    - post-tempest
-
 - include: stackviz.yml
   when: run_tempest|bool
   tags:
     - run-stackviz
   ignore_errors: yes
+
+- include: post-tempest.yml
+  when: post_tempest|bool
+  tags:
+    - post-tempest