Fix after merge

Author: Rafał Hibner

cpp/src/arrow/acero/groupby_aggregate_node.cc

@@ -70,7 +70,7 @@ Status GroupByNode::Init() {
     std::unique_ptr<arrow::acero::BackpressureControl> backpressure_control =
         std::make_unique<BackpressureController>(inputs_[0], this);
     ARROW_ASSIGN_OR_RAISE(auto handler,
-                          BackpressureHandler::Make(this, low_threshold, high_threshold,
+                          BackpressureHandler::Make(low_threshold, high_threshold,
                                                     std::move(backpressure_control)));
 
     processor_ = acero::util::SerialSequencingQueue::Processor::MakeBackpressureWrapper(
@@ -507,4 +507,4 @@ Status GroupByNode::InitLocalStateIfNeeded(ThreadLocalState* state) {
 
 }  // namespace aggregate
 }  // namespace acero
-}  // namespace arrow
+}  // namespace arrow

cpp/src/arrow/acero/scalar_aggregate_node.cc

@@ -235,7 +235,7 @@ Status ScalarAggregateNode::Init() {
     std::unique_ptr<arrow::acero::BackpressureControl> backpressure_control =
         std::make_unique<BackpressureController>(inputs_[0], this);
     ARROW_ASSIGN_OR_RAISE(auto handler,
-                          BackpressureHandler::Make(this, low_threshold, high_threshold,
+                          BackpressureHandler::Make(low_threshold, high_threshold,
                                                     std::move(backpressure_control)));
 
     processor_ = acero::util::SerialSequencingQueue::Processor::MakeBackpressureWrapper(
@@ -376,4 +376,4 @@ Status ScalarAggregateNode::OutputResult(bool is_last) {
 
 }  // namespace aggregate
 }  // namespace acero
-}  // namespace arrow
+}  // namespace arrow