[FIX] point_of_sale: total banner have proper background in refund of products

Steps to reproduce:

- Go to Point of Sale app.
- Create a new order with many items in it (until you need to scroll).
- Go to Orders > Click on 'All active orders' and select 'Paid'.
- Scroll throught the items in the right.

Issue:

The total summary has a transparent background, so it will overlap with
the items inside the order and make less clear to visualize the total.

Solution:

Added the `background: inherit` to the `summary` class in the
pos.scss so we get the right background that we need for this view.

FW - port: master

opw-3093131

closes odoo/odoo#107993

X-original-commit: 3edd7f5cc425d991c512e278c22ee44043bc9d86
Signed-off-by: Trinh Jacky (trj) <trj@odoo.com>
Signed-off-by: Maruan Aguerdouh Mohtar (magm) <magm@odoo.com>

addons/point_of_sale/static/src/scss/pos.scss

@@ -2185,6 +2185,7 @@ td {
     padding: map-get($spacers, 2) map-get($spacers, 3);
     border-top: 1px solid $gray-200;
     box-sizing: border-box;
+    background:  inherit;
 }
 .pos .order .summary .total {
     font-size: 22px;