tieBreakLessThan
fun tieBreakLessThan(first: TopDocs.ShardRef, firstDoc: ScoreDoc, second: TopDocs.ShardRef, secondDoc: ScoreDoc, tieBreaker: Comparator<ScoreDoc>): Boolean
Use the tie breaker if provided. If tie breaker returns 0 signifying equal values, we use hit indices to tie break intra shard ties