Incorrect "total" value in search in nested index

[eguguchkin]

We have deduplication for list of IDS

if total == 0 || lastID != id { // lids increase monotonically, it's enough to compare current id with the last one
	ids = append(ids, seq.IDSource{ID: id})
}
lastID = id

But we didn't have it for total calculation. To use deduplication logic, we need to convert LID to seq.ID, this requires reading MIDs and RIDs blocks from disk, which slows down the query.

An additional problem is that in the context of performing a search, we have no information that a nested index is involved in the search, and we cannot decide to take the more expensive branch for the "total".

See iterateEvalTree() function in frac/processor/search.go