[mistral] Create for all client and non-client lib xena branch

This creates the stable/xena branch for all client
and non-client libraries now that we are past the
lib freeze on September 02.

If a team wants to wait for a specific patch to make it to the library,
someone from the team can -1 the patch to have it held,or update that
patch with a different commit SHA.

Patches with no response will be merged by Friday, September 10.

Change-Id: I791fd0a3e42c83c2e4952b514949f7402dd3918d

deliverables/xena/mistral-extra.yaml

@@ -11,3 +11,6 @@ releases:
     projects:
       - repo: openstack/mistral-extra
         hash: acd70beba1bdf7189291a6a1a65ce45393ecac6d
+branches:
+  - name: stable/xena
+    location: 11.1.0

deliverables/xena/mistral-lib.yaml

@@ -11,3 +11,6 @@ releases:
     projects:
       - repo: openstack/mistral-lib
         hash: 44c33f2ccd8b059f68db59114c71ba95dfae574d
+branches:
+  - name: stable/xena
+    location: 2.5.0

deliverables/xena/python-mistralclient.yaml

@@ -11,3 +11,6 @@ releases:
     projects:
       - repo: openstack/python-mistralclient
         hash: 608ec45cef72d822d1242e0aefcea7d044662adc
+branches:
+  - name: stable/xena
+    location: 4.3.0