Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/34670
Users can enable the New Architecture on iOS in two way: using the `RCT_NEW_ACRH_ENABLED` env variable or setting the `new_arch_enabled` flag when invoking the `use_react_native` function.
We need to set the `RCT_NEW_ACRH_ENABLED` even when the other method is used because we need to inject that flag into the codebase.
## Changelog
[iOS][Fixed] Make sure to turn on the `RCT_NEW_ACRH_ENABLED` flag
Reviewed By: cortinico
Differential Revision: D39430904
fbshipit-source-id: abb55642b4c72d7dec8b045fb4a43c1763f0ee0f