Don't register Babel in Jest preprocessor (#36522)

Summary:
Pull Request resolved: #36522

We don't need to register Babel for internal tests, Jest takes care of hooking require. This resolves an internal require-clobbering issue.

Changelog: [Internal]

Reviewed By: GijsWeterings

Differential Revision: D44197281

fbshipit-source-id: ee076d431b0c49ae4a2da609d964cdd66bca27f8

packages/react-native/jest/private/preprocessor.js

@@ -24,9 +24,11 @@ const nodeFiles = new RegExp(
     '/metro(?:-[^/]*)?/', // metro, metro-core, metro-source-map, metro-etc.
   ].join('|'),
 );
-const nodeOptions = babelRegisterOnly.config([nodeFiles]);
 
-babelRegisterOnly([]);
+// Use metro-babel-register to build the Babel configuration we need for Node
+// files, but Jest takes care of hooking require so we don't actually register
+// Babel here.
+const nodeOptions = babelRegisterOnly.config([nodeFiles]);
 
 const transformer = require('metro-react-native-babel-transformer');
 module.exports = {