[4.0][mod_articles_category] Remove unused variable

[SharkyKZ]

Pull Request for Issue # .

Summary of Changes

Removes unused variable.

Testing Instructions

Code review.

Documentation Changes Required

No.

[Quy]

I have tested this item ✅ successfully on f10095e

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[alikon]

I have tested this item ✅ successfully on f10095e

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[Quy]

RTC

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[wilsonge]

Thanks!