RN: Patch enableEagerAlternateStateNodeCleanup into Renderers (OSS) (facebook#51856) (#81)

Summary:
Pull Request resolved: facebook#51856

Enables the `enableEagerAlternateStateNodeCleanup` feature flag in the open source React Native renderers that are currently targeting React 19.1, by manually patching them in the React Native repository.

This feature flag has been found to significantly improve memory management of parent alternate fibers in persistent modes (i.e. Fabric), and we want this to be available to open source users of React Native before the next scheduled public version release of React.

For more details about the fix, see: facebook/react#33161

Changelog:
[General][Changed] - Reduces memory usage, by improving memory management of parent alternate fibers. (Previously, a parent fiber might retain memory associated with shadow nodes from a previous commit.)

Reviewed By: rickhanlonii

Differential Revision: D76073900

fbshipit-source-id: 6779ea0862d4a1e25354b12ef3d1363dc12d26cc

Co-authored-by: Tim Yung <yungsters@meta.com>

Author: hannojg

packages/react-native/Libraries/Renderer/implementations/ReactFabric-dev.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<e233b479345be01ec0cc3c6e337839a2>>
+ * @generated SignedSource<<6b3694149dd8856f0c741d3d94e05646>>
  *
  * This file was sync'd from the facebook/react repository.
  */
@@ -10483,6 +10483,8 @@ __DEV__ &&
             (offscreenSubtreeWasHidden ||
               null === current ||
               safelyDetachRef(current, current.return));
+          null !== finishedWork.alternate &&
+            (finishedWork.alternate.stateNode = finishedWork.stateNode);
           break;
         case 6:
           recursivelyTraverseMutationEffects(root, finishedWork);

packages/react-native/Libraries/Renderer/implementations/ReactFabric-prod.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<558b9dfa7f6550519be8c208c6bc0eef>>
+ * @generated SignedSource<<7430b56dac3186eca669ae53bbf1f23d>>
  *
  * This file was sync'd from the facebook/react repository.
  */
@@ -8005,6 +8005,8 @@ function commitMutationEffectsOnFiber(finishedWork, root) {
         (offscreenSubtreeWasHidden ||
           null === current ||
           safelyDetachRef(current, current.return));
+      null !== finishedWork.alternate &&
+        (finishedWork.alternate.stateNode = finishedWork.stateNode);
       break;
     case 6:
       recursivelyTraverseMutationEffects(root, finishedWork);

packages/react-native/Libraries/Renderer/implementations/ReactFabric-profiling.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<e1a70389fe3fab3ec5907522444da7d2>>
+ * @generated SignedSource<<cf19390911979c415bb5e95c5270fba6>>
  *
  * This file was sync'd from the facebook/react repository.
  */
@@ -8488,6 +8488,8 @@ function commitMutationEffectsOnFiber(finishedWork, root) {
         (offscreenSubtreeWasHidden ||
           null === current ||
           safelyDetachRef(current, current.return));
+      null !== finishedWork.alternate &&
+        (finishedWork.alternate.stateNode = finishedWork.stateNode);
       break;
     case 6:
       recursivelyTraverseMutationEffects(root, finishedWork);