Handle the case when enableNullHandling is true and an aggregation function is used w/ a column that has an empty null bitmap

[nizarhejazi]

Handle the case when enableNullHandling is true and null bitmap is empty.

bugfix

[codecov-commenter]

Codecov Report

Merging #9566 (e606f9f) into master (65e01f1) will increase coverage by 0.13%.
The diff coverage is 96.15%.

@@             Coverage Diff              @@
##             master    #9566      +/-   ##
============================================
+ Coverage     68.53%   68.67%   +0.13%     
+ Complexity     5219     5209      -10     
============================================
  Files          1931     1931              
  Lines        103111   103119       +8     
  Branches      15654    15654              
============================================
+ Hits          70669    70817     +148     
+ Misses        27435    27246     -189     
- Partials       5007     5056      +49     

Flag	Coverage Δ
integration1	25.88% <0.00%> (?)
integration2	?
unittests1	67.35% <96.15%> (+0.03%)	⬆️
unittests2	15.68% <0.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...y/aggregation/function/MaxAggregationFunction.java	72.41% <93.33%> (+1.78%)	⬆️
...y/aggregation/function/MinAggregationFunction.java	72.41% <93.33%> (+1.78%)	⬆️
...y/aggregation/function/AvgAggregationFunction.java	83.45% <100.00%> (+1.77%)	⬆️
...y/aggregation/function/SumAggregationFunction.java	72.65% <100.00%> (+2.02%)	⬆️
...t/core/plan/StreamingInstanceResponsePlanNode.java	0.00% <0.00%> (-100.00%)	⬇️
...ore/operator/streaming/StreamingResponseUtils.java	0.00% <0.00%> (-100.00%)	⬇️
...server/starter/helix/SegmentReloadStatusValue.java	0.00% <0.00%> (-100.00%)	⬇️
...ager/realtime/PeerSchemeSplitSegmentCommitter.java	0.00% <0.00%> (-100.00%)	⬇️
...urces/ServerReloadControllerJobStatusResponse.java	0.00% <0.00%> (-100.00%)	⬇️
...he/pinot/common/utils/grpc/GrpcRequestBuilder.java	0.00% <0.00%> (-90.91%)	⬇️
... and 234 more

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