Summary:
`-all` is the **default** for projects generated by Android Studio, and it provides **additional sources** helpful for debugging. It's also much more likely to already exist on a developer's machine (which has built other Android projects), avoiding additional downloads and saving disk space.
`-all` has also been the variant used in `react-native` for all versions prior to 5bc67b658e.
Follow-up to https://github.com/facebook/react-native/issues/29613
## Changelog
[Android] [Changed] - Use Gradle Wrapper 6.6 (-all variant)
Pull Request resolved: https://github.com/facebook/react-native/pull/29793
Test Plan: No test needed since versions are the same.
Reviewed By: fkgozali
Differential Revision: D23406546
Pulled By: mdvacca
fbshipit-source-id: b74dbbfc0317bccf1940b1e5062d866e50aed28a
3a8559b86c