Otherwise attachments have a high chance to disappear with akkoma-fe’s
“delete & redraft” feature when cleanup is enabled in the backend. Since
we don't know whether a deletion was intended to be part of a redraft
process or even if whether the redraft was abandoned we still have to
delete attachments eventually.
A thirty minute delay should provide sufficient time for redrafting.
Fixes: https://akkoma.dev/AkkomaGang/akkoma/issues/775