Remove react-native-exit-app from nightly testing (#51230)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/51230

react-native-exit-app last commit is from 2 years ago.
Removing it as it is broken with our nightly integration

## Changelog:
[Internal] - Remove react-native-exit-app from nightly testing

Reviewed By: cortinico

Differential Revision: D74527792

fbshipit-source-id: 0974b2d857aa6f76c59b0411204798a5fe48cffe