[FIX] sale: do not focus on custom value in product configurator

When the product configurator is opened, the focus is always on the
custom value input, which may scroll down the configurator and make the
user miss attributes

Steps to reproduce:
1. Install Sales
2. Go to Settings > Sales > Product Catalog and enable Product
   Configurator and save
3. Go to Sales > Products > Products and open product 'Cabinet with
   Doors'
4. Go to the 'Attributes & Variants' tab and create and edit an
   attribute 'Custom'
5. Add a value 'Notes' and check 'Is custom value' and save
6. Add the value to the product and save
7. Open product 'Customizable Desk', in the 'Sales' tab, add 'Cabinet
   with Doors' to the Optional Products and save
8. Create a new quotation and add product 'Customizable Desk'
9. The product configurator opens up with the focus on the 'Custom'
   attribute input, if the window has a small height, it scrolls down to
   that input

Solution:
Remove the focus on the custom value input

Problem:
The focus was made on the input of custom values

opw-3057390

closes odoo/odoo#113301

X-original-commit: dd3e5be00cc4e3408d90abb3923b6658fb1d3073
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>
Signed-off-by: Guillaume Merlin (megu) <megu@odoo.com>

addons/sale/static/src/js/variant_mixin.js

@@ -151,7 +151,6 @@ var VariantMixin = {
                     if (previousCustomValue) {
                         $input.val(previousCustomValue);
                     }
-                    $input[0].focus();
                 }
             } else {
                 $variantContainer.find('.variant_custom_value').remove();