[FIX] web: External Link
[FIX] web: External Link

- Install Sales
- Go to Sales > Orders > Customers, 'Invoicing' tab
- Add a Bank Account

The 'External Link' button (which allows opening the form view) on the
bank account is not visible.

More generally, in the case of a One2many list view in a `<group>` tag,
the 'External Link' button of a Many2one field (which allows opening
the form view) is not visible.

The `flex: 1 0 auto;` should not be applied in the list view.

Corresponding PR in v11: #28812
opw-1903158

closes odoo/odoo#28741
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo