[FIX] website: fix access error at settings save

Let a database with company C1, C2,
and a website W belonging to C1, used for both companies.
Settings in C2 cannot be saved without setting a website.
At settings load W is removed from C2 because it belongs to C1.
So reset C2's website to W.
This triggers a (useless) write of company_id (C1.id) on W.
Then we have w.user_id.company_id.id != self.env.user.company_id.id, (C1 != C2).
So if contacts are not shared, then accessing w.user_id.company_id would cause
an access error because of record rules, preventing the save.
As a result, settings are unusable for company C2.

opw 2008887

closes odoo/odoo#34102

Signed-off-by: Denis Ledoux <beledouxdenis@users.noreply.github.com>