fix the various GetAggregateStatesInATimeInterval (Async and not)

[tonyx]

Those functions returns objects depending on the fact that they have a snapshot or not.
This must be fixed because snapshots should be only commodities meant to boost performances.
No business decision should depend on having a snapshot or not.

Leave the if they are meant as euristic for statistical purposes, but provide anyway a realistic and realable
alternative that has a behavior that doesn't depend on having a snapshot or not.