Remove unsupported puppet 5 code
Remove unsupported puppet 5 code

Prior to this commit, there was a block of code checking for puppet 5,
which we no longer support.

This commit aims to clean up this unnecesary code in order to keep the
module tidy.

puppetlabs/puppetlabs-docker,puppetlabs/puppetlabs-docker,puppetlabs/puppetlabs-docker