Assign yardstick/barometer to ericsson-build4

This is a temporary fix until we can determine the full list of
requirements from each project needed for the opnfv-build-ubuntu labled
servers.

Previously these were building fine on ericsson-build4, so reassigning
them there should keep there builds green.

Change-Id: I767b6faa718cd6dd4b9fd17f83e7ee817cfb8c4d
Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>