Gate on octavia-v2-dsvm-tls-barbican

At the Shanghai PTG, members of the Barbican and Octavia teams seemed to
agree that job octavia-v2-dsvm-tls-barbican could be made voting in both
projects. The job has proven to be quite stable over time [1].

The patch that make the job voting in Octavia is [2].

[1] http://zuul.openstack.org/builds?job_name=octavia-v2-dsvm-tls-barbican
[2] https://review.opendev.org/#/c/697644/

Change-Id: I56dd4b92ccb2545a9b46c743647af11aaa5c94f8

.zuul.yaml

@@ -168,6 +168,7 @@
         - barbican-vault-devstack-functional
         - barbican-grenade-devstack
         - barbican-simple-crypto-devstack-tempest-ipv6-only
+        - octavia-v2-dsvm-tls-barbican
         # TripleO jobs that deploy Barbican.
         # Note we don't use a project-template here, so it's easier
         # to disable voting on one specific job if things go wrong.
@@ -177,8 +178,6 @@
         # failures, please reach us on #tripleo IRC channel.
         - tripleo-ci-centos-7-scenario002-standalone:
             voting: false
-        - octavia-v2-dsvm-tls-barbican:
-            voting: false
     gate:
       queue: barbican
       jobs:
@@ -189,6 +188,7 @@
         - barbican-vault-devstack-functional
         - barbican-grenade-devstack
         - barbican-simple-crypto-devstack-tempest-ipv6-only
+        - octavia-v2-dsvm-tls-barbican
     experimental:
       jobs:
         - barbican-kmip-devstack-functional