tests/qtest/migration: Print migration incoming errors

We're currently just asserting when incoming migration fails. Let's
print the error message from QMP as well.

Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240104142144.9680-6-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
1 file changed