qemuxml2argvtest: Add pre-blockdev post-werror-move version of 'disk-error-policy'

qemuxml2argvtest: Add pre-blockdev post-werror-move version of 'disk-error-policy'

Starting with qemu-3.0 release we use the 'werror' and 'rerror'
properties with the frontend (device) rather than the storage backend
(with a minor caveat of s390, where we use it earlier as it doesn't
 support USB disks, and other disk types supported it earlier).

Add specific test cases after the change, but before '-blockdev' was
enabled.

This is done separately from the changes in the next commit which simply
moves all other disk tests to the last pre-blockdev qemu as we have a
semantic change happening after 2.12.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>