Temporarily remove tripleo-ci nodepool provider

The tripleo-ci cloud is suffering an extended outage, and nodepool
still seems to have some issues dealing with this. We're temporarily
removing it until it comes back on line, at which point we can
revert this change.

Change-Id: I2095a96ed6bb30f14c3191523ce9a277e239c9b4
Merge "Temporarily remove tripleo-ci nodepool provider"