remove Collector specializations [LUCENE-5229]

There are too many collector specializations (i think 16 or 18?) and too many crazy defaults like returning NaN scores to the user by default in indexsearcher.

this confuses hotspot (I will ignore any benchmarks posted here where only one type of sort is running thru the JVM, thats unrealistic), and confuses users with stuff like NaN scores coming back by default.

I have two concerete suggestions:

- nuke doMaxScores. its implicit from doScores. This is just over the top. This should also halve the collectors.
- change doScores to true by default in indexsearcher. since shai was confused by the NaNs by default, and he added this stuff to lucene, that says **everything** about how wrong this default is. Someone who **does** understand what it does can simply pass false.

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Migrated from [LUCENE-5229](https://issues.apache.org/jira/browse/LUCENE-5229) by Robert Muir (@rmuir)
Sub-tasks:
- #6296