Deprecated ubuntu-xenial-otc nodeset (apache#221)

ubuntu-xenial-otc nodeset is only used in cloud-provider-openstack nested
vm scenario, no project refer this job cloud-provider-openstack-unittest-nested,
so we can deprecate nodeset at first.

Closes: theopenlab/openlab#61

Author: kiwik

zuul.d/jobs.yaml

@@ -198,7 +198,7 @@
     description: |
       Run Kubernetes openstack-cloud-controller-manager unit test in devstack instance
     run: playbooks/cloud-provider-openstack-unittest-nested/run.yaml
-    nodeset: ubuntu-xenial-otc
+    nodeset: ubuntu-xenial
 
 # Kubernetes cloud-provider-openstack jobs
 - job:

zuul.d/nodesets.yaml

@@ -18,12 +18,6 @@
       - name: ubuntu-xenial-ut
         label: ubuntu-xenial-ut
 
-- nodeset:
-    name: ubuntu-xenial-otc
-    nodes:
-      - name: ubuntu-xenial-otc
-        label: ubuntu-xenial-otc
-
 - nodeset:
     name: ubuntu-xenial-vexxhost
     nodes: