This PR removes the livechat's discuss route overrides
that added `cors="*"` since they are not safe (different databases on our
cloud are considered as SameSite).
In the meantime, embed livechats won't work as expected since cors is
prevented and will be fixed in a following PR.
closesodoo/odoo#135260
Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>