[ENT-9538] Fixed index mapping for scatter chart

[mahamakifdar19]

Ticket
https://2u-internal.atlassian.net/browse/ENT-9538

Description
Fixed index mapping for scatter chart. Updated the method to derive the index from the original data array instead of filteredData to ensure correct marker sizes.

For all changes

• Ensure adequate tests are in place (or reviewed existing tests cover changes)

Only if submitting a visual change

• Ensure to attach screenshots
• Ensure to have UX team confirm screenshots

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.62%. Comparing base (b06faa9) to head (50d46f4).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1327   +/-   ##
=======================================
  Coverage   85.61%   85.62%           
=======================================
  Files         576      576           
  Lines       12697    12700    +3     
  Branches     2693     2649   -44     
=======================================
+ Hits        10871    10874    +3     
- Misses       1765     1766    +1     
+ Partials       61       60    -1     

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