[FIX] website_sale: fix behaviors for loading recently viewed products

If there is no product in the recently viewed product snippet, it will
simply not be shown. It appears only if there are products (with some
flickering we may decide to improve in future versions).

Also fix the behavior when the last product of the snippet is moved to
the cart.

task-2076271

closes odoo/odoo#37371

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>
Co-authored-by: qsm-odoo <qsm@odoo.com>