migration: Respect exit-on-error when migration fails before resuming

migration: Respect exit-on-error when migration fails before resuming

When exit-on-error was added to migration, it wasn't added to postcopy.
Even though postcopy migration will usually pause and not fail, in cases
it does unrecoverably fail before destination side has been started,
exit-on-error will allow management to query the error.

Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20251103183301.3840862-7-jmarcin@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>