[FIX] website: allow again external website redirect

Broken by commit [1], where only the `url_to` should've been part of the
check for 301/302. The rest of the `if` was about relative URL check,
routing map check and converter check, all related to 308 only.

Note that in the meantime, commit [2] was added in those checks and
needs to be part of 301/302 too.

[1]: https://github.com/odoo/odoo/commit/14a850976711431f36b7f889ea9cf31b1114513d
[2]: https://github.com/odoo/odoo/commit/26fa923f6ab01298bf1a1e9f6a615c9aa9e2e5ed

Fixes https://github.com/odoo/odoo/issues/129290



closes odoo/odoo#129410

Signed-off-by: Benoit Socias (bso) <bso@odoo.com>