ceph-dev-pipeline: Locate ceph-dev-new-setup builds automatically

c-d-p takes an optional param `SETUP_BUILD_ID` which can be pointed at a previously-completed ceph-dev-new-setup build, and use its artifacts instead of invoking its own c-d-n-s build. This saves a lot of time on rebuilds, but only if one remembers to manually insert the parameter.

It would be even better if c-d-p could locate one automatically via (most likely) calls to the Jenkins REST API.