Only upload logs when jobs fail

We're having some major disk issues. Help the situation by only
uploading failure logs.

Change-Id: I4156fb59570d98b16c775752639c2fe23e5777c5

roles/upload-logs/tasks/main.yaml

@@ -2,6 +2,11 @@
   include_role:
     name: set-zuul-log-path-fact
 
+# NOTE(mordred) Temporary hack to only upload logs on failures to work around
+# unfortunately timed disk outage.
+- when: not zuul_success|bool
+  block:
+
     - name: Create log directories
       file:
         path: "{{zuul_logserver_root}}/{{ zuul_log_path }}"