templates: approve_receipts: Use only /get_image/
templates: approve_receipts: Use only /get_image/

No longer use /full_image/ for the full size images as /get_image/ can
now handle these.

Signed-off-by: Andrew Clayton <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@opentechlabs.co.uk>

ac000/receiptomatic