merge aggregators in `src/storage/aggregator.xx` and `hybridse/src/vm/aggregator.h`

**Describe the feature you'd like**
There are two different places to implement the pre-aggregation logics for the `long window` feature. We should finally merge these in order to avoid code duplication.

The issue mentions merging aggregators in `src/storage/aggregator.xx` and `hybridse/src/vm/aggregator.h`. First, examine these two files to understand the pre-aggregation logic for the 'long window' feature. Look for overlapping code and design a unified implementation. Check for existing tests related to aggregators to ensure the merge does not break functionality. The goal is to eliminate duplication while maintaining the same behavior.

Scritto dal modello di indicizzazione a partire dal testo della issue.