[Minor] Small refactor of raw index creator constructor to be more clear

[Jackie-Jiang]

• For version before v4, only numDocsPerChunk is required
• For version v4, only chunkSize is required

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 73.91304% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 62.15%. Comparing base (59551e4) to head (453b99c).
Report is 409 commits behind head on master.

Files	Patch %	Lines
...or/impl/fwd/SingleValueVarByteRawIndexCreator.java	28.57%	3 Missing and 2 partials ⚠️
...r/impl/fwd/MultiValueFixedByteRawIndexCreator.java	87.50%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #13093      +/-   ##
============================================
+ Coverage     61.75%   62.15%   +0.40%     
+ Complexity      207      198       -9     
============================================
  Files          2436     2507      +71     
  Lines        133233   137790    +4557     
  Branches      20636    21328     +692     
============================================
+ Hits          82274    85647    +3373     
- Misses        44911    45757     +846     
- Partials       6048     6386     +338     

Flag	Coverage Δ
custom-integration1	<0.01% <0.00%> (-0.01%)	⬇️
integration	<0.01% <0.00%> (-0.01%)	⬇️
integration1	<0.01% <0.00%> (-0.01%)	⬇️
integration2	0.00% <0.00%> (ø)
java-11	62.12% <73.91%> (+0.41%)	⬆️
java-21	35.22% <0.00%> (-26.40%)	⬇️
skip-bytebuffers-false	62.14% <73.91%> (+0.39%)	⬆️
skip-bytebuffers-true	35.20% <0.00%> (+7.47%)	⬆️
temurin	62.15% <73.91%> (+0.40%)	⬆️
unittests	62.15% <73.91%> (+0.40%)	⬆️
unittests1	46.84% <0.00%> (-0.05%)	⬇️
unittests2	27.74% <73.91%> (+0.01%)	⬆️

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