Add new DoNotStrip class to proguard config (#27934)

Summary:
JNI now comes from https://github.com/facebookincubator/fbjni and it uses a different DoNotStrip class (https://github.com/facebookincubator/fbjni/blob/master/java/com/facebook/jni/annotations/DoNotStrip.java) so we need to include it in the proguard config.

## Changelog

[Android] [Fixed] - Add new DoNotStrip class to proguard config
Pull Request resolved: https://github.com/facebook/react-native/pull/27934

Test Plan: Test that it fixes a crash related to missing NativeRunnable class in release builds.

Differential Revision: D19690580

Pulled By: cpojer

fbshipit-source-id: cb4e2eaae35fb3a9d68f04c57cc973914207be73