[FIX] web: Allow users to enable list view with group_by_no_leaf

- Go to accounting/Report/Invoices Analysis
- Open studio
- enable list view
- empty view

This code bellow compute count_field as `__count` because group_by_no_leaf
is in the context.

But in the basic_model we don't consider this case.

https://github.com/odoo/odoo/blob/5797fd80a63309269f15bcbe4948d4429a53eec2/odoo/models.py#L2293-L2297



opw-2980923

closes odoo/odoo#100869

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>