message: simplify GetGlobalState
diff: @@ -23,8 +23,7 @@ public:
  };
  unique_ptr<GlobalOperatorState> PhysicalCrossProduct::GetGlobalState(ClientContext &context) {
  - auto state = make_unique<CrossProductGlobalState>();
  - return move(state);
  + return make_unique<CrossProductGlobalState>();
  }
  void PhysicalCrossProduct::Sink(ExecutionContext &context, GlobalOperatorState &state, LocalSinkState &lstate_,
  