[Concurrent Segment Search] Dynamic cluster setting to disable concurrent segment search for a given aggregation type

[jed326]

As a part of #9316 it looks like it would be useful to have a way to disable concurrent segment search when certain aggregator types are used. This could be especially useful in the case of custom aggregator plugins that we do not have any knowledge of but due to how they are implemented either perform worse with or are completely unable to support concurrent aggregations.

A possible alternative would be to extend the AggregatorFactory with a supportsConcurrentSearch() method however this would require code level changes for any existing plugins while a dynamic cluster setting less intrusive to the plugins and should be able to be modified without any downtime or disruptions.