Use kni-cloud node for cloud jobs

And kni-baremetal for baremetal jobs.  The two long-lived jenkins
nodes prd-kni-baremetal-1 and -2 are different; one has cloud
credentials, the other is for bare metal deployments.  Use the
more specific kni-cloud and kni-baremetal labels (already present
on the nodes) to select them for the appropriate jobs.

Signed-off-by: James E. Blair <jeblair@redhat.com>
Change-Id: I20c9601934e8e9b5bdb89c56ef168985891c4fdd