groupArrayLast merge behaviour

AggregatingMergeTree + groupArrayLast probably could store the last N inserted values.

But it does not work

```sql
select finalizeAggregation( groupArrayLastArrayState(3)([1,2,3]) + groupArrayLastArrayState(3)([4]) ) x;
┌─x───────┐
│ [4,2,3] │
└─────────┘
```

it would be nice to have another result:

```
┌─x───────┐
│ [2,3,4] │
└─────────┘
```