Add cinder v2 experimental job

Tempest adding new cinder v2 job
- https://review.openstack.org/#/c/570466/

and running that as experimental to cover the v2
testing.

This commit add that job running on cinder experimental
pipeline also.

Depends-On: https://review.openstack.org/#/c/570466/
Change-Id: I69fd45311675591c2b772205b2f4780555cb8556

.zuul.yaml

@@ -39,6 +39,18 @@
               - ^releasenotes/.*$
 
         - openstack-tox-lower-constraints
+    experimental:
+      jobs:
+        - tempest-cinder-v2-api:
+            irrelevant-files:
+              - ^.*\.rst$
+              - ^api-ref/.*$
+              - ^cinder/hacking/.*$
+              - ^cinder/locale/.*$
+              - ^cinder/tests/unit.*$
+              - ^contrib/block-box.*$
+              - ^doc/.*$
+              - ^releasenotes/.*$
 - job:
     # Previously named legacy-tempest-dsvm-full-lio
     name: cinder-tempest-dsvm-lvm-lio-barbican