Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/36958

As we don't invoke `buck` anymore inside `Dockerfile.android` anymore,
those instructions can be removed.

Changelog:
[Internal] [Changed] - Remove instructions from `Dockerfile.android` that are BUCK related

Reviewed By: sammy-SC, arushikesarwani94

Differential Revision: D45086054

fbshipit-source-id: 5ed5e353f43b11784a4dcb930148ab264d4dd063