Summary:
This moves the `helloworld` app to build from the artifacts produced by build_npm_package so that we don't rebuild ReactNative Android from source 8 times.
It reduces build time of such jobs from 14mins to 4mins, resulting in 80mins of build time for every test_all run.
## Changelog:
[INTERNAL] - Move helloworld to build from artifacts on Android
Pull Request resolved: https://github.com/facebook/react-native/pull/45517
Test Plan: CI
Reviewed By: blakef
Differential Revision: D59957613
Pulled By: cortinico
fbshipit-source-id: b6c4adcf804af6c8d2661cf56549d037e09aa2c1
Nicola Corti