install_modules: cleanup /etc/puppet/modules
install_modules: cleanup /etc/puppet/modules

Make sure there is no puppet modules pre-installed in the image where we
run integration testing by cleaning up the /etc/puppet/modules/*
directory.

Change-Id: I489717356b75b95c1a881b6f3e554cfec66ee6f1

openstack/puppet-openstack-integration,openstack/puppet-openstack-integration,openstack/puppet-openstack-integration