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: Ibecf830a6b49688f439e3ac47efc53150405a4e6

fuel-infra/puppet-ironic,toby82/puppet-ironic,openstack/puppet-ironic,trown/puppet-ironic,openstack/puppet-ironic,trown/puppet-ironic,trown/puppet-ironic,rdo-puppet-modules/puppet-ironic,openstack/puppet-ironic,fuel-infra/puppet-ironic,fuel-infra/puppet-ironic,toby82/puppet-ironic,rdo-puppet-modules/puppet-ironic