spec_helper: Remove unneccesary stubbing
spec_helper: Remove unneccesary stubbing

This only roots all Facter instances into memory, while something already
creates a new Facter instance each run.

fuel-infra/puppetlabs-stdlib,puppetlabs/puppetlabs-stdlib,DavidS/puppetlabs-stdlib,yadavnikhil/puppetlabs-stdlib,HelenCampbell/puppetlabs-stdlib,jbondpdx/puppetlabs-stdlib