Correct `puppet module list` check in beaker
Correct `puppet module list` check in beaker

The final check during the prep stage, where `puppet module list` is
run so that its output can be used for debugging, should run on the
current host in the loop, not the first host in the array.

Change-Id: Id17d26acda26b5baaac3bb5f616738201aa99044

openstack/puppet-vswitch,redhat-cip/puppet-vswitch,plumgrid/puppet-vswitch,openstack/puppet-vswitch,rdo-puppet-modules/puppet-vswitch,squarit/puppet-vswitch