Bump react-native-gradle-plugin to 0.71.2

Summary:
We need to bump & publish a new version of the Gradle Plugin.
This is needed otherwise the template will break as I start to remove
entries from the `Android-prebuilt.cmake` file

Changelog:
[Internal] [Changed] - Bump react-native-gradle-plugin to 0.71.2

Reviewed By: lunaleaps, mdvacca

Differential Revision: D39815785

fbshipit-source-id: b140187971e2f963ef459e9c83ce9a76e67c89bd