[Tempest Plugins] Tag stein-last

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

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

This tag will help for testing the stable/stein with single
compatible tag of Tempest and its plugins.

Tagging 'stein-last' as well as a new version also with same hash.
Documenting this new tag name here
- https://review.opendev.org/c/openstack/project-team-guide/+/769821

More detail on compatible version policy for Tempest and its
plugins is here
- https://docs.openstack.org/tempest/latest/tempest_and_plugins_compatible_version_policy.html

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

Change-Id: Iae762866024bcdeb5e4dbc7c50421861499f7c19

deliverables/stein/senlin-tempest-plugin.yaml

@@ -12,3 +12,7 @@ releases:
       - repo: openstack/senlin-tempest-plugin
         hash: c5796721c4ae4916bd1f68ba8f1f8d0c7309d2b5
     version: 0.2.0
+  - version: stein-last
+    projects:
+      - repo: openstack/senlin-tempest-plugin
+        hash: a85b110a1dafff478320931878e75e0591e4158c

deliverables/wallaby/senlin-tempest-plugin.yaml

@@ -8,3 +8,8 @@ repository-settings:
   openstack/senlin-tempest-plugin: {}
 team: senlin
 type: tempest-plugin
+releases:
+  - version: 1.2.0
+    projects:
+      - repo: openstack/senlin-tempest-plugin
+        hash: a85b110a1dafff478320931878e75e0591e4158c