[FIX] website_slides: allow portal users to read their own reviews with attachment

Followup of 86c80d341846894c435b1c8f61ef946b06e72ec7 : currently portal users face an access issue
if they try to read their full review with attachments. This commit fixes that
by sudo-ing access to the attachment as other access is already granted.

Task ID 2214795

X-original-commit: ad7cd4bd38fdb0d92b22bb979637bb5623621378