ExplainPlanV2 should get trimmed list for regionserver location

PHOENIX-6907 introduces way for ExplainPlan to provide list of regionserver locations that are accessed by the query during execution. It also introduces config "phoenix.max.region.locations.size.explain.plan" to restrict max region locations to be displayed as part of the Explain plan output. However, the trimmed list was intentionally meant for query output version of ExplainPlan only, not for ExplainPlanV2 based explain plan output.

However, given the convenience provided by ExplainPlanV2 objects, it is far easier to use it by client applications rather than breaking down the String based old explain plan. It would be better to keep trimmed list of regionserver for ExplainPlanV2 as well, rather than keeping full list around in the objects.