Docs: Fix DataGridAggregationExample

[ScarletKuro]

Description

Fixes: #7466

How Has This Been Tested?

Visually

Type of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (fix or improvement to the website or code docs)

Checklist

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.11%. Comparing base (28bc599) to head (ff6337e).
Report is 101 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8772      +/-   ##
==========================================
+ Coverage   89.82%   90.11%   +0.28%     
==========================================
  Files         412      419       +7     
  Lines       11878    12195     +317     
  Branches     2364     2401      +37     
==========================================
+ Hits        10670    10990     +320     
+ Misses        681      662      -19     
- Partials      527      543      +16     

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