Use fetch-subunit-output role

Currently there is a zuul-jobs role only used in this tempest job while
other jobs mostly use fetch-subunit-output role.

This changes tries to consolidate towards the most used role, to be able
to clean up zuul-jobs a bit.

Change-Id: I404760ba34767660f8816f48712e13dccad67440
Depends-On: https://review.openstack.org/548406
diff --git a/playbooks/post-tempest.yaml b/playbooks/post-tempest.yaml
index ab7a1bb..4dde2c9 100644
--- a/playbooks/post-tempest.yaml
+++ b/playbooks/post-tempest.yaml
@@ -1,7 +1,6 @@
 - hosts: all
   become: true
   roles:
-    - role: process-test-results
-      test_results_dir: '{{ devstack_base_dir }}/tempest'
-      tox_envdir: tempest
+    - role: fetch-subunit-output
+      zuul_work_dir: '{{ devstack_base_dir }}/tempest'
     - role: process-stackviz