Group and count plan stages do not set the WorkingSetID output on PlanStage::DEAD state

As of this commit all uses of PlanExecutor are expecting a valid status member object on any type of failure in getNext(). If the executor dies at this spot in the group stage then the plan executor attempts to build a valid status member object which fails somewhat silently when the WorkingSetID is invalid.

Still working on a simpler repro...