ci: run cache-repear only on main repo (#45943)

Summary:
This PR fixes Cache repear
## Changelog:

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[INTERNAL] [FIXED] - Cache repear job

Pull Request resolved: https://github.com/facebook/react-native/pull/45943

Test Plan: CI Green

Reviewed By: blakef

Differential Revision: D60962822

Pulled By: cortinico

fbshipit-source-id: 453153005bbc1b99dbe569eb6be77d17c8a176db