Remove unused build-from-source input (#45533)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/45533

This input is unused and is causing a warning on the build pipeline.
I'm cleaning it up.

Changelog:
[Internal] [Changed] - Remove unused build-from-source input

Reviewed By: blakef

Differential Revision: D59958184

fbshipit-source-id: 23ba010da077342605afaaee122bc7ceabc89915