Fix benchmarks to work with new aggregation types

[davidwendt]

Fixes benchmarks compile errors introduced by #10357

Example:

/cudf/cpp/benchmarks/reduction/reduce.cpp: In function ‘void BM_reduction(benchmark::State&, const std::unique_ptr<cudf::aggregation>&)’:
/cudf/cpp/benchmarks/reduction/reduce.cpp:52:46: error: invalid initialization of reference of type ‘const std::unique_ptr<cudf::reduce_aggregation>&’ from expression of type ‘const std::unique_ptr<cudf::aggregation>’
   52 |     auto result = cudf::reduce(input_column, agg, output_dtype);

Aggregation types for reduce and scan were modified to include template types.

[codecov]

Codecov Report

Merging #10428 (6928347) into branch-22.04 (0be0b00) will increase coverage by 0.01%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-22.04   #10428      +/-   ##
================================================
+ Coverage         86.13%   86.15%   +0.01%     
================================================
  Files               139      139              
  Lines             22438    22438              
================================================
+ Hits              19328    19332       +4     
+ Misses             3110     3106       -4     

Impacted Files	Coverage Δ
python/cudf/cudf/core/column/string.py	88.39% <0.00%> (+0.12%)	⬆️
python/cudf/cudf/core/groupby/groupby.py	91.57% <0.00%> (+0.22%)	⬆️
python/cudf/cudf/core/tools/datetimes.py	84.49% <0.00%> (+0.30%)	⬆️
python/cudf/cudf/core/column/lists.py	90.56% <0.00%> (+0.47%)	⬆️

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[vyasr]

Thanks for fixing this! I merged these changes locally and verified that they fix the build.

[vyasr]

@gpucibot merge