Refactor WeekdayOfTheMonthIndex class component to functional component

[Manik-Khajuria-5]

Issue number

Contributes to #4460

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Description

This pull request refactors the WeekdayOfTheMonthIndex component by converting it from a legacy class-based React component to a modern, hook-based functional component.

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Key Changes

• Converted WeekdayOfTheMonthIndex from a class component to a functional component
• Replaced lifecycle methods with appropriate React hooks (useIntl)
• Ensured no behavioral or UI regressions
• Maintained full feature parity with the previous implementation

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