Use UPPER_CONSTRAINTS_FILE for stable/wallaby testing

stable/wallaby is in EM state and Tempest is going to be
pinned for stable/wallaby which need to modify run-tempest
role to use the constraints set by the devstack.

Change-Id: I985c222a1a461dff10ff33716fd2263a1a89813a
diff --git a/roles/run-tempest/tasks/main.yaml b/roles/run-tempest/tasks/main.yaml
index f302fa5..e569e53 100644
--- a/roles/run-tempest/tasks/main.yaml
+++ b/roles/run-tempest/tasks/main.yaml
@@ -25,11 +25,11 @@
     target_branch: "{{ zuul.override_checkout }}"
   when: zuul.override_checkout is defined
 
-- name: Use stable branch upper-constraints till stable/victoria
+- name: Use stable branch upper-constraints till stable/wallaby
   set_fact:
     # TOX_CONSTRAINTS_FILE is new name, UPPER_CONSTRAINTS_FILE is old one, best to set both
     tempest_tox_environment: "{{ tempest_tox_environment | combine({'UPPER_CONSTRAINTS_FILE': stable_constraints_file}) | combine({'TOX_CONSTRAINTS_FILE': stable_constraints_file}) }}"
-  when: target_branch in ["stable/ocata", "stable/pike", "stable/queens", "stable/rocky", "stable/stein", "stable/train", "stable/ussuri", "stable/victoria"]
+  when: target_branch in ["stable/ocata", "stable/pike", "stable/queens", "stable/rocky", "stable/stein", "stable/train", "stable/ussuri", "stable/victoria", "stable/wallaby"]
 
 - name: Use Configured upper-constraints for non-master Tempest
   set_fact: