Make sure we don't run RN CI on forks (#53707)

Summary:
We had reports from the Community of the RN CI running on forks and causing high costs and bills for them
This change should make sure that the most impactful jobs only runs on the React Native CI and not on forks.

## Changelog:
[Internal] -

Pull Request resolved: https://github.com/facebook/react-native/pull/53707

Test Plan: GHA

Reviewed By: cortinico

Differential Revision: D82107313

Pulled By: cipolleschi

fbshipit-source-id: ff7f418344975e7bb8306a6356d774c26bea3db1