Remove unused _callbacks hashmap (#33097)
Remove unused _callbacks hashmap (#33097)

Summary:
Stumbled upon this unused code.

## Changelog

[Internal] [Fixed] - Remove unused _callbacks hashmap

Pull Request resolved: https://github.com/facebook/react-native/pull/33097

Test Plan: Test it still builds

Reviewed By: philIip

Differential Revision: D34215314

Pulled By: ShikaSD

fbshipit-source-id: 7357a9be725d57b37f697f7222b95c1fd1d9f67c

javache/react-native,javache/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,javache/react-native,facebook/react-native,facebook/react-native,janicduplessis/react-native,janicduplessis/react-native,janicduplessis/react-native,facebook/react-native,facebook/react-native,javache/react-native,javache/react-native,janicduplessis/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,facebook/react-native,javache/react-native,facebook/react-native,javache/react-native,javache/react-native,javache/react-native,facebook/react-native