FOI: minimalistic test case

[yarikoptic]

now we have a dedicated to inventories bucket (main one still goes into dandiarchive for now), where we have one for dandisets/ prefix of dandiarchive bucket:

dandi@drogon:~$ aws s3 ls s3://dandiarchive-inventory/dandiarchive/dandiset-manifest/
                           PRE 2024-12-20T01-00Z/
                           PRE 2024-12-21T01-00Z/
                           PRE data/
                           PRE hive/

dandi@drogon:~$ aws s3 ls s3://dandiarchive-inventory/dandiarchive/dandiset-manifest/data/
2024-12-21 10:27:16          0 
2024-12-20 16:21:18   28711737 aeee7c6c-e8e8-4caf-adac-b6ee3bced18d.csv.gz
2024-12-21 13:23:46   28713840 c15823ab-9099-41b8-97b5-9cfb5fd198e6.csv.gz

which should be (didn't check) identical to the main inventory in terms of columns collected, but residing in non-public bucket (accessible from dandi at drogon)

(note that 0 empty key -- the one @jwodder observed and now ignored since #96).