chore: rename polyfills to js-polyfills (umbrella 480) (#34574)

Summary:
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[General] [Changed] - Rename polyfills to js-polyfills as part of https://github.com/react-native-community/discussions-and-proposals/pull/480

Pull Request resolved: https://github.com/facebook/react-native/pull/34574

Reviewed By: cipolleschi

Differential Revision: D39268818

Pulled By: hoxyq

fbshipit-source-id: c87807460f27fc83667d18c350a4a847459f056e