Retire horizon-cisco-ui project

The horizon-cisco-ui project has been retired. This completes step 5
of the retirement process:

https://docs.openstack.org/infra/manual/drivers.html#retiring-a-project

Change-Id: Ice73c045abad2eef1790a62281979e16d4407250

reference/legacy.yaml

@@ -233,6 +233,10 @@ horizon:
       retired-on: 2016-12-02
       repos:
         - openstack/django-openstack-auth-kerberos
+    horizon-cisco-ui:
+      retired-on: 2018-02-07
+      repos:
+        - openstack/horizon-cisco-ui
 
 Infrastructure:
   irc-channel: openstack-infra

reference/projects.yaml

@@ -544,9 +544,6 @@ horizon:
         - assert:follows-standard-deprecation
         - assert:supports-upgrade
         - stable:follows-policy
-    horizon-cisco-ui:
-      repos:
-        - openstack/horizon-cisco-ui
     tempest-horizon:
       repos:
         - openstack/tempest-horizon