Bug 31041: Prevent duplicate display of cashup summary when printing

Bug 31041: Prevent duplicate display of cashup summary when printing

To test:
1. Have POS on.
2. Have some registers and items for sale. Make some sales to 'Cashup'.
3. If you have enough enough lines in the table so that 'register.pl' would print on 2 or more pages, the summary will be duplicated that same number of time.

If you are lazy like me and don't want to make that many transaction you can also add some content to the page like this:

for (let i = 0; i < 100; i++) {
  $('#register').append('<h1>TEST</h1>');
}

4. APPLY PATCH, clear browser cahche
5. Try printing again, you should only get one cashup summary when printing.

Signed-off-by: Juliet Heltibridle <jheltibridle@rcplib.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>