Further refine the Gradle caching logic. (#45233)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/45233

We want the Gradle cache to be written only on main/-stable branches run, and only for jobs with `cache-read-only` == false (i.e. `build_android`).
This changes implements it.

Changelog:
[Internal] [Changed] - Further refine the Gradle caching logic.

Reviewed By: blakef

Differential Revision: D59225944

fbshipit-source-id: b6c3a5d4d0d399d6fe42287976925c43f3f12eb7