SearchThresholdAdjustingQueryRunner and TopNQueryQueryToolChest.ThresholdAdjustingQueryRunner sanity

[leventov]

Those classes don't make sense to me. E. g. with TopN, whether the query threshold is 3 or 300 or 3000, it always could make sense to have per-historical / per-segment threshold (is this what is meant by "minTopNThreshold", right?) of 1000. They are independent. Also it's really hard to understand how the manipulation happens across broker/historical boundary, because within a Historical it's a wastful no-op (extend the threshold and then trim the results again).

For SearchThresholdAdjustingQueryRunner, Iterables.limit() modification is a no-op (because query.getLimit() is bigger than config.getMaxSearchLimit()).

@gianm @drcrallen

[github-actions]

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