Before this commit, users returning from Adyen to Odoo after payment could see their session renewed, depending on their browser's implementation of the `SameSite` cookie attribute. This prevented Odoo from retrieving the transaction from the users' session. This commit flags the return route of Adyen with `save_session=False`, hence allowing all users to immediately post-process their transactions when they return to Odoo. While we're at it, the docstrings of the return routes of PayUmoney and SIPS' have been updated for better clarity. closes odoo/odoo#74763 Signed-off-by: Antoine Vandevenne (anv) <AntoineVDV@users.noreply.github.com>