lib namespace: Remove unnecessary init files

Those files were added there mainly to mirror qemu,
since that is used as a module, since for that
case we do use things like

from qemu.tests import block_copy

That's not needed for libvirt, and we'd like to
dump it from qemu as well, although it needs
more care.

This solves a problem where it's not possible
to import the python library bindings on virt-test,
since the libvirt module present in virt-test would
take precedence over the library installed system
wide.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>