Test using sahara tempest plugin

Tempest tests for sahara were moved out of the tempest repo into their
own plugin repo. Update the functional test playbook to run tests
provided by the sahara tempest plugin.

Change-Id: Ic12bccd6eac91163e21dfd4de9eabb99498ca599
Closes-Bug: 1638883

tests/os_sahara-overrides.yml

@@ -13,5 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Ref: https://bugs.launchpad.net/openstack-ansible/+bug/1638883
-tempest_git_install_branch: 93a0c668d9b39c619eb67ed2ae6b74074d4626e5
+tempest_plugins:
+  - name: sahara-tests
+    repo: https://git.openstack.org/openstack/sahara-tests
+    branch: master

tests/test-sahara-functional.yml

@@ -19,6 +19,6 @@
     - name: Run tempest
       shell: |
         . {{ tempest_venv_bin }}/activate
-        {{ tempest_venv_bin | dirname }}/run_tempest.sh --no-virtual-env --serial data_processing
+        {{ tempest_venv_bin | dirname }}/run_tempest.sh --no-virtual-env --serial sahara_tempest_plugin.tests.api
   vars_files:
     - common/test-vars.yml