Use beaker-puppet_install_helper to install puppet

Use beaker-puppet_install_helper to install puppet

When running with BEAKER_provision=no, the following happens:

In Trusty: beaker is running dpkg with '--force' option so even
if Puppet is already installed, the return code will be 0.
In CentOS: beaker is running 'rpm -ivh' the second time and since
the package is already here, the return code will be 1.

Using the new puppet install helper will abort installing puppet
if BEAKER_provision is no, so tests will continue as normal.

Change-Id: Ifeada55370bbd5b30418447c8fc1da101de2b774
Co-Authored-By: Colleen Murphy <colleen@gazlene.net>