After the edit ran, a batch can still fail the redaction checks: a
deleted marked page alongside added pages, or text still shown under a
mark. Both returned without discard_edit_callbacks, so globals (and now
timers) the batch's field scripts left stayed in the document's realm
while the document rolled back. Every other refusal after the edit
already discards them.
Test: a_batch_a_redaction_check_refuses_discards_callback_globals. A
keystroke script sets a global, and a batch that sets the field and
deletes the marked page while adding one is refused. Without the fix the
global is still there ("number" for "undefined").