Turn down yum install-packages
Turn down yum install-packages

When debugging, this is very noisy for very little value.  If we need
to specifically debug this script we can turn up the level.

Change-Id: Ie15f16397c37e718aa919853697cbf2c5c08503c

switch-ch/diskimage-builder,openstack/diskimage-builder,zioproto/diskimage-builder,zioproto/diskimage-builder,switch-ch/diskimage-builder,openstack/diskimage-builder