…nded max scores.

When a query contains a mandatory clause that doesn't track the max score per
block, we disable the max score optimization. Previously, we were doing this by
wrapping the collector with a FilterCollector that always returned
ScoreMode.COMPLETE.

However we weren't adjusting totalHitsThreshold, so the collector could still
call Scorer#setMinCompetitiveScore. It is against the method contract to call
setMinCompetitiveScore when the score mode is COMPLETE, and some scorers like
ReqOptSumScorer throw an error in this case.

This commit tries to disable the optimization by always setting
totalHitsThreshold to max int, as opposed to wrapping the collector.

…uiting the total hit count.