Stop running k8s-on-openstack nested

The current code runs k8s-on-openstack's ansible in an ansible
task. This makes debugging failures especially difficult.

Instead, move the prep task to update-system-config, which will
ensure the repo is cloned, and move the post task to its own
playbook. The cinder storage class k8s action can be removed from
this completely as it's handled in the rook playbook.

Then just run the k8s-on-openstack playbook as usual, but without
the cd first so that our normal ansible.cfg works.

Change-Id: I6015e58daa940914d46602a2cb64ecac5d59fa2e

playbooks/update-system-config.yaml

@@ -18,3 +18,11 @@
       command: ansible-galaxy install --roles-path /etc/ansible/roles --force -r roles.yaml
       args:
         chdir: /opt/system-config
+
+    - name: Make sure k8s-on-openstack repo is up to date
+      git:
+        repo: https://github.com/infraly/k8s-on-openstack
+        dest: /opt/k8s-on-openstack
+        # HEAD as of 2019-02-08
+        version: e27a313b1583c377e08385014b9a880da765924b
+        force: yes