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: I2cb734defce21ed1709e80bd0f0b0d965b772a9d
b4f3e89ed9