virsh_update_device: Replace --persistent with --live

Adjust the test to use the newer --live option rather than --persistent.

Also fix issue with shut_off_option testing.  When a guest is off, the
failure should only be if someone passed the --live flag.  Add the
shut_off_option testing to the normal_test list and use the diff_file
check to ensure that a shutdown guest would be updated.  The --live
option processing should only affect the running guest and not the
configuration after shutdown

Signed-of-by: John Ferlan <jferlan@redhat.com>