Remove globals defined for the React renderer that are now unused (react#58454)

Summary:
Pull Request resolved: react#58454

The OSS renderer has been upgraded and it's no longer consuming these globals.

Changelog: [internal]

Reviewed By: christophpurrer

Differential Revision: D119498576

Author: rubennorte

packages/react-native/Libraries/Core/setUpTimers.js

@@ -20,12 +20,6 @@ if (__DEV__) {
 
 // In bridgeless mode, timers are host functions installed from cpp.
 if (global.RN$Bridgeless === true) {
-  // This is the flag that tells React to use `queueMicrotask` to batch state
-  // updates, instead of using the scheduler to schedule a regular task.
-  // We use a global variable because we don't currently have any other
-  // mechanism to pass feature flags from RN to React in OSS.
-  global.RN$enableMicrotasksInReact = true;
-
   polyfillGlobal(
     'queueMicrotask',
     () =>

packages/react-native/src/private/setup/setUpDOM.js

@@ -95,12 +95,4 @@ export default function setUpDOM() {
     'CustomEvent',
     () => require('../webapis/dom/events/CustomEvent').default,
   );
-
-  // Expose a global function that the React renderer can call to check
-  // if EventTarget-based event dispatching is enabled.
-  // We use a global function because we don't have another mechanism to pass
-  // feature flags from RN to React in OSS (similar to RN$enableMicrotasksInReact
-  // in setUpTimers.js).
-  global.RN$isNativeEventTargetEventDispatchingEnabled = () =>
-    require('../featureflags/ReactNativeFeatureFlags').enableNativeEventTargetEventDispatching();
 }