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/roles/process-stackviz/tasks/main.yaml b/roles/process-stackviz/tasks/main.yaml
index 09de606..82f8f3d 100644
--- a/roles/process-stackviz/tasks/main.yaml
+++ b/roles/process-stackviz/tasks/main.yaml
@@ -9,11 +9,11 @@
 
 - name: Check if subunit data exists
   stat:
-    path: "{{ stage_dir }}/{{ test_results_stage_name }}.subunit"
+    path: "{{ zuul_work_dir }}/testrepository.subunit"
   register: subunit_input
 
 - debug:
-    msg: "Subunit file could not be found at {{ stage_dir }}/{{ test_results_stage_name }}.subunit"
+    msg: "Subunit file could not be found at {{ zuul_work_dir }}/testrepository.subunit"
   when: not subunit_input.stat.exists
 
 - name: Install stackviz