The compute manager should be virt-driver agnostic for the
most part. This reference to errors in post-live migration
for QEMU predates gerrit and goes back to a diablo commit
with no further explanation of what's going on with this
change, but it looks like it's what added live migration
way back when:
1518e66d0c
It doesn't even make sense now, so remove it.
Change-Id: I144711f9e000c7e723f3b4e3dce56e3e922cf6e4
(cherry picked from commit b6996365d3)