Make OnBatchCompleteListener interface internal (#53409)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53409

This interface is public and is part of Legacy Architecture.

Having this interface as `public` was a mistake, as users can't really do much with it.
There is only one old library that is going to be affected by this change:
https://github.com/spoke-ph/react-native-threads
The library appears unmaintained since RN 0.69 + no NewArch support so I won't consider this a breaking change
given this will land in 0.82.

I'm making it internal so we can remove it more easily later.

Changelog:
[Android] [Changed] - Make OnBatchCompleteListener interface internal

Differential Revision: D80715625

fbshipit-source-id: 94fe80eeba95222deab7ca89c5fcafca8fcee0b7