AZ605: Links used for inheritance can't expire

A shared relation that inheritance follows (shortcut : folder shared, can view = ... or shortcut.view) is part of a stored tree, so its shares can't expire, start later or carry a caveat. Remove those shares' expiry (or the shares) before applying, and don't give new ones.

Reported when the policy is applied (rowfence push, apply, a migration), against the database.