[FIX] website_form: fix form redirection to an anchor in the same page

Before this commit, when the redirection of a form was an anchor and
that anchor link came from the anchor option, the scroll animation was
not triggered.

task-2172312

closes odoo/odoo#81596

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