qemu: capabilities: update qemu-4.2 capabilities for s390x

qemu: capabilities: update qemu-4.2 capabilities for s390x

Update s390x capabilities for QEMU 4.2 with the actual GA version for
QEMU and on the latest z15 machine.

This picks up the new blockdev capability, so we need to refresh a bunch
of test cases as well.

Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>