Do not run Maven jobs on jclouds slaves.

Maven jobs are not currently able to build on jclouds slaves. As soon as
the Maven build portion of these jobs starts exceptions are thrown and
the jobs fail. Work around this by forcing Maven jobs to run on slaves
without the jclouds node label.

Change-Id: I5dc6b9c5109e9095a1636b7fc0b92c4df79f609b
Reviewed-on: https://review.openstack.org/22587
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Khai Do <zaro0508@gmail.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins