Fix compilation errors in groupby benchmarks. (#9072)

Fixes a couple of compilation errors caused by new groupby_aggregation class.

Authors:
  - https://github.com/nvdbaranec

Approvers:
  - Christopher Harris (https://github.com/cwharris)
  - Ram (Ramakrishna Prabhu) (https://github.com/rgsl888prabhu)
  - Nghia Truong (https://github.com/ttnghia)
  - MithunR (https://github.com/mythrocks)

URL: #9072

cpp/benchmarks/groupby/group_nth_benchmark.cu

@@ -63,7 +63,8 @@ void BM_pre_sorted_nth(benchmark::State& state)
   std::vector<cudf::groupby::aggregation_request> requests;
   requests.emplace_back(cudf::groupby::aggregation_request());
   requests[0].values = vals;
-  requests[0].aggregations.push_back(cudf::make_nth_element_aggregation<groupby_aggregation>(-1));
+  requests[0].aggregations.push_back(
+    cudf::make_nth_element_aggregation<cudf::groupby_aggregation>(-1));
 
   for (auto _ : state) {
     cuda_event_timer timer(state, true);

cpp/benchmarks/groupby/group_sum_benchmark.cu

@@ -58,7 +58,7 @@ void BM_basic_sum(benchmark::State& state)
   std::vector<cudf::groupby::aggregation_request> requests;
   requests.emplace_back(cudf::groupby::aggregation_request());
   requests[0].values = vals;
-  requests[0].aggregations.push_back(cudf::make_sum_aggregation());
+  requests[0].aggregations.push_back(cudf::make_sum_aggregation<cudf::groupby_aggregation>());
 
   for (auto _ : state) {
     cuda_event_timer timer(state, true);
@@ -97,7 +97,7 @@ void BM_pre_sorted_sum(benchmark::State& state)
   std::vector<cudf::groupby::aggregation_request> requests;
   requests.emplace_back(cudf::groupby::aggregation_request());
   requests[0].values = vals;
-  requests[0].aggregations.push_back(cudf::make_sum_aggregation());
+  requests[0].aggregations.push_back(cudf::make_sum_aggregation<cudf::groupby_aggregation>());
 
   for (auto _ : state) {
     cuda_event_timer timer(state, true);