doc/develop/py_testing.rst: Update section on filesystem images

Now that we have no users of "virt-make-fs" nor users of "sudo" for
creating disk images update the documentation. We remove packages that
are no longer required (and related text) as well as be firm in our
wording around not using "sudo".

Signed-off-by: Tom Rini <trini@konsulko.com>
1 file changed