Fix test_android_template (#44871)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44871

This re-enables and fix `test_android_template`.
The problem was that we were invoking `yarn install` inside the template after we already installed with `npm install --registry`.
So this was invalidating the Verdaccio setup and effectively fetching packages from NPM

Changelog:
[Internal] [Changed] - Fix test_android_template

Reviewed By: cipolleschi

Differential Revision: D58407941

fbshipit-source-id: 9b7b877cfc994eb8db1b5bf71dd35289c3937f5c