Set infracloud-vanilla servers to zero.
The infracloud vanilla mirror is currently down.  This patch
sets the max servers to zero until the issue is fixed to avoid
gate failures.
@@ -839,7 +839,7 @@ providers:
cloud: infracloud-vanilla
api-timeout: 60
boot-timeout: 120
- max-servers: 96
+ max-servers: 0
nodepool-id: 'nodepool.openstack.org'
rate: 0.25
image-type: 'qcow2'
