xlconfigtests: use qemu-xen in all test data files

xlconfigtests: use qemu-xen in all test data files

Some of the test configuration files in tests/xlconfigdata
use the old qemu-dm as the emulator. Many of the configuration
features tested (spice, rbd, multi-usb) are not even usable with
the old qemu. Change these files to use the new qemu-xen (also
known as qemu upstream) emulator.

Note: This change fixes xlconfigtest failures when the old
qemu is actually installed on the system. During device post
parse, the libxl driver attempts to invoke the emulator to
determine if it is the old or new qemu so it can properly set
video RAM defaults. With the old qemu installed, the default
video RAM was set differently than the expected value.
Changing all the test data files to use qemu-xen ensures
predictable results wrt default video RAM size.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>