Stop syncing ReactTypes to RN (#18366)

This is a really old one and all callers have since been codemodded away
anyway because of problems.

This file is not really as rigorously maintained as the official Flow types
but has a few more specifics. However, the inconsistency causes problems
when you try to pass files typed using the built-in Flow typing for React
and mix it with these.

We just happen to get away with it because we compile out the types. If we
didn't we would hit those problems by even using these in our renderers.

scripts/rollup/packaging.js

@@ -87,11 +87,9 @@ async function copyWWWShims() {
 }
 
 async function copyRNShims() {
-  const reactTypesBuildTarget = 'build/react-native/shims/ReactTypes.js';
   await Promise.all([
     // React Native
     asyncCopyTo(`${__dirname}/shims/react-native`, 'build/react-native/shims'),
-    asyncCopyTo(require.resolve('shared/ReactTypes.js'), reactTypesBuildTarget),
     asyncCopyTo(
       require.resolve('react-native-renderer/src/ReactNativeTypes.js'),
       'build/react-native/shims/ReactNativeTypes.js'