[draft]Add a new distinctCountGlobal function

[xiangfu0]

Add a new distinctCountGlobal function to implement a sharable ConcurrentHashMap to update distinct values to avoid many hashset merges. This is much faster for large distinct counts queries

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 26.80412% with 142 lines in your changes missing coverage. Please review.

Project coverage is 63.38%. Comparing base (59551e4) to head (0291849).
Report is 1753 commits behind head on master.

Files with missing lines	Patch %	Lines
...nction/DistinctCountGlobalAggregationFunction.java	0.00%	116 Missing ⚠️
...e/operator/combine/AggregationCombineOperator.java	67.12%	14 Missing and 10 partials ⚠️
...org/apache/pinot/core/common/ObjectSerDeUtils.java	66.66%	0 Missing and 1 partial ⚠️
...gregation/function/AggregationFunctionFactory.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #15117      +/-   ##
============================================
+ Coverage     61.75%   63.38%   +1.63%     
- Complexity      207     1480    +1273     
============================================
  Files          2436     2749     +313     
  Lines        133233   154635   +21402     
  Branches      20636    23838    +3202     
============================================
+ Hits          82274    98013   +15739     
- Misses        44911    49211    +4300     
- Partials       6048     7411    +1363     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (+99.99%)	⬆️
integration	100.00% <ø> (+99.99%)	⬆️
integration1	100.00% <ø> (+99.99%)	⬆️
integration2	0.00% <ø> (ø)
java-11	63.36% <26.80%> (+1.65%)	⬆️
java-21	63.26% <26.80%> (+1.63%)	⬆️
skip-bytebuffers-false	63.36% <26.80%> (+1.61%)	⬆️
skip-bytebuffers-true	63.26% <26.80%> (+35.53%)	⬆️
temurin	63.38% <26.80%> (+1.63%)	⬆️
unittests	63.37% <26.80%> (+1.63%)	⬆️
unittests1	55.97% <26.80%> (+9.07%)	⬆️
unittests2	33.95% <0.00%> (+6.21%)	⬆️

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