[FIX] point_of_sale: hide 'loading' text when printing

When we are using auto_print without iot box, the 'print()' function on
window is called, and if we are validating a invoiced order, the
download of invoice will let a blockUI over the receipt screen.

To  avoid printing 'Loading' on the receipts, we are not displaying the
blockUI when we print, as it is never expected.

OPW-2199489

closes odoo/odoo#46528

X-original-commit: 54a3ef53e94a756c8635b708b9f187aefc8c5c8b
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/point_of_sale/static/src/css/pos.css

@@ -1569,6 +1569,9 @@ td {
     .o_chat_window {
         display: none !important;
     }
+    .blockUI {
+        display: none !important;
+    }
 }
 
 /* d) The Scale screen */