Only use datafiles and initsys addon outside virtualenvs

To make it so that cloud-init is installable in a virtualenv
where it can be tested in an isolated scenario we need to avoid
using and including datafiles (which won't be written into the
virtualenv) and also avoid using our initsys helper class which
also adds on its own files when we are being ran from a virtualenv.
Only use datafiles and initsys addon outside virtualenvs

To make it so that cloud-init is installable in a virtualenv
where it can be tested in an isolated scenario we need to avoid
using and including datafiles (which won't be written into the
virtualenv) and also avoid using our initsys helper class which
also adds on its own files when we are being ran from a virtualenv.