openstack-tox-molecule: replace success-url and failure-url

Fixed issue introduced by new logs browsing experience where
success-url and failure-url are no longer working.

Change-Id: Id8a3202235ea48129aa7883b00a2a3095cadf6fe
Needed-By: https://review.opendev.org/#/c/669223/

playbooks/tox-molecule/post.yaml

@@ -0,0 +1,11 @@
+- hosts: all
+  tasks:
+    - name: Return artifact to Zuul
+      zuul_return:
+        data:
+          zuul:
+            artifacts:
+              - name: "Molecule report"
+                url: "tox/reports.html"
+                metadata:
+                  type: html_report

zuul.d/jobs.yaml

@@ -209,8 +209,7 @@
       Runs molecule to test Ansible roles.
 
       Uses tox with the ``molecule`` environment.
-    success-url: "tox/reports.html"
-    failure-url: "tox/reports.html"
+    post-run: playbooks/tox-molecule/post.yaml
     vars:
       bindep_profile: test molecule