Tune cleanup_old_versions request rate to S3 rate limits

[wjones127]

A user reported that they easily hit rate limits deleting a lot of versions.

https://discord.com/channels/1030247538198061086/1321118496247250954

Given their situation, I'm guessing they had 57,000 versions to delete. Each with a data file, manifest, and transaction file. So that's 171,000 objects to delete.

We should see if we can keep within rate limits if we have tens of thousands of objects we need to delete, and tune our rate limits appropriately.