(packaging) Remove etc directory references from packaging

In commit d091bf882d731232ebcbf8d1dc324593cc837a98, facter.conf and the etc
directory were removed from facter. This commit removes the references to the
etc directory from the osx file mapping file and ext/project_data.yaml, which
is used to build the gem and tarball. Without this commit building the gem or
tarball will fail trying to copy a nonexistent directory.