Remove more dead code
Remove more dead code

Images that are uploaded to nova-lxd are always a split image
so remove the code that allows non split images since it was
never used.

Signed-off-by: Chuck Short <753a8074f04ffd62a8fff7516e3ae689be8e35ad@canonical.com>

tpouyer/nova-lxd,tpouyer/nova-lxd