[FIX] website_sale: still cleaning lost references to deleted code in website_sale ...

Fixed checkout redirection that was meant to clean the session (incorrect sale order or transaction) that may happen
when having issues with the payment.
[CLEAN] Use none or false, but not both on two lines ...
Merge pull request #164 from odoo-dev/master-website_sale--fix-tde

[FIX] website_sale: cleaned call to removed methods in website_sale