[tempest] Tag xena-last

Xena branch is in Extended Maintenance now[1]. Tempest and
tempest plugins are branchless which means master version of
Tempest and its plugins is used to test the supported stable
branches.

Once any stable branch is moved to EM state then, Tempest and
its plugins compatible tag[2] needs to be released so that we can
keep testing the EM stable branches with that tag once master
Tempest and its plugins are not compatible[3].

Tagging 'xena-last' with the same hash of new tag 35.0.0 which mark
the end of support for stable/xena in Tempest.

[1] https://releases.openstack.org/xena/index.html
[2] https://docs.openstack.org/tempest/latest/stable_branch_support_policy.html
[3] https://docs.openstack.org/tempest/latest/tempest_and_plugins_compatible_version_policy.html

Change-Id: I41e2cfbf8014ac91bfdfe5cd0aa755d943fb15b7

deliverables/bobcat/tempest.yaml

@@ -13,3 +13,7 @@ releases:
       - repo: openstack/tempest
         hash: 8d1521977436947834acba42f9f855cb1d8e5135
     version: 34.2.0
+  - projects:
+      - repo: openstack/tempest
+        hash: 3d29d5e3ba5de63f8109843fe786c69dc8943f46
+    version: 35.0.0

deliverables/xena/tempest.yaml

@@ -22,3 +22,7 @@ releases:
       - repo: openstack/tempest
         hash: d02fe845247bb7dcfe2beda0b81e08e53e8bc745
     version: 29.0.0
+  - projects:
+      - repo: openstack/tempest
+        hash: 3d29d5e3ba5de63f8109843fe786c69dc8943f46
+    version: xena-last