Avoid Unauthorized error in the subscriber

When a content items is modified, this subscriber kicks in and copies the language independent field values to all translations. However, it might be possible that the current user does not have the required permissions on all translations.

Therefore, trying to fetch all translations (unconditionally) can lead to an Unauthorized error. => Use the restricted fetcher (similar to the recent change e7328f08fec2a4104cbe1969c5bfeae1820a42ff)