Bug 36998: Correctly update the 'Amount paid' displayed on the issue refund modal

Bug 36998: Correctly update the 'Amount paid' displayed on the issue refund modal

To test:
1) Enable the 'EnablePointOfSale' sys pref (also requires the 'UseCashRegisters' pref)
2) In the POS module, configure a cash register and also configure some items for purchase with different costs
3) Make multiple sales
4) View the transactions table by clicking the 'Cash summary for ...' tab and then clicking on your cash register's name.
5) Click on the 'Issue refund' button for one of the sales, this should have the correct 'Amount paid'
6) Close the modal and click issue refund on your other item.
7) Note the 'Amount paid' is incorrect and lists the value from the previous item
8) Apply patch
9) Now when clicking issue refund, it displays the correct 'Amount paid'

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>