Added tempest_black_regex to skip tempest tests

* https://review.openstack.org/547106 adds a black_regex flag to
  tempest run. We can use the same in devstack-tempest base job
  to skip/blacklist tests.

Change-Id: I9ed91b01ddb7ec0a3d23305031afbac7c4b16c55
diff --git a/roles/run-tempest/tasks/main.yaml b/roles/run-tempest/tasks/main.yaml
index b68507a..54ddc71 100644
--- a/roles/run-tempest/tasks/main.yaml
+++ b/roles/run-tempest/tasks/main.yaml
@@ -35,7 +35,9 @@
       when: blacklist_stat.stat.exists
 
 - name: Run Tempest
-  command: tox -e {{tox_envlist}} -- {{tempest_test_regex|quote}} {{blacklist_option|default('')}} --concurrency={{tempest_concurrency|default(default_concurrency)}}
+  command: tox -e {{tox_envlist}} -- {{tempest_test_regex|quote}} {{blacklist_option|default('')}} \
+            --concurrency={{tempest_concurrency|default(default_concurrency)}} \
+            --black-regex={{tempest_black_regex|quote}}
   args:
     chdir: "{{devstack_base_dir}}/tempest"
   become: true