[FIX] sale: fix the discount layout for the mobile screen

Steps to reproduce: (for small devices)

- install the sales app
- activate discounts in the sale setting
- create a sale order and add the product
- click on the discount button and check the pop-up

The full text cannot be displayed in one line due to the lack of space.
So, providing sufficient space for displaying the entire text
of the radio button in a single line.

task-3568058

closes odoo/odoo#140612

Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>

addons/sale/wizard/sale_order_discount_views.xml

@@ -11,7 +11,7 @@
                     <field name="company_id" invisible="1"/>
                     <field name="currency_id" invisible="1"/>
                     <div class="row">
-                        <div class="col-3">
+                        <div class="col-sm-5 col-md-4 col-lg-4 col-4">
                             <group>
                                 <label for="discount_amount" string="Discount" invisible="discount_type != 'amount'"/>
                                 <field name="discount_amount" invisible="discount_type != 'amount'" nolabel="1"/>
@@ -23,7 +23,7 @@
                                        widget="percentage" nolabel="1"/>
                             </group>
                         </div>
-                        <div class="col-3">
+                        <div class="col-sm-7 col-md-8 col-lg-8 col-8">
                             <field name="discount_type" widget="radio"/>
                         </div>
                     </div>