Remove qemu-kvm in favor of qemu-system.

The former is the default on new servers but causes some
weird issues that prevent live migration.  qemu-kvm
seems to assume that spice is installed and running
even if it's not installed.

Change-Id: I104f239f1d8dce5c14a91a7a83b215e331270019
Merge "Remove qemu-kvm in favor of qemu-system." into production