The 7d85ab1eac refactor of 'ir.http' introduced changes in `web/image` that
caused the route to no longer return early (to avoid data processing steps)
in the case of redirection and that caused `binary_content` to not set the
mimetype of the `ir.attachment` when it was an URL.
This commit fixes those issues, allowing `web/image` to redirect properly.
closes odoo/odoo#30777