[flags] enable opt-in for enableDefaultTransitionIndicator (#34373)

So we can test the feature.

DiffTrain build for [3168e08](3168e08)

Author: rickhanlonii

compiled-rn/VERSION_NATIVE_FB

@@ -1 +1 @@
-19.2.0-native-fb-2805f0ed-20250903
+19.2.0-native-fb-3168e08f-20250903

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-dev.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<2a251f735691d41de05784cc3922bd3a>>
+ * @generated SignedSource<<e16d4d0e56b0093108153a8e5c2fa6ec>>
  */
 
 "use strict";
@@ -404,5 +404,5 @@ __DEV__ &&
     exports.useFormStatus = function () {
       return resolveDispatcher().useHostTransitionStatus();
     };
-    exports.version = "19.2.0-native-fb-2805f0ed-20250903";
+    exports.version = "19.2.0-native-fb-3168e08f-20250903";
   })();

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-prod.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<23caf0525b005a476914b4fd14108776>>
+ * @generated SignedSource<<5c28310e31f7b026d9838c06862fa435>>
  */
 
 "use strict";
@@ -203,4 +203,4 @@ exports.useFormState = function (action, initialState, permalink) {
 exports.useFormStatus = function () {
   return ReactSharedInternals.H.useHostTransitionStatus();
 };
-exports.version = "19.2.0-native-fb-2805f0ed-20250903";
+exports.version = "19.2.0-native-fb-3168e08f-20250903";

compiled-rn/facebook-fbsource/xplat/js/RKJSModules/vendor/react/react-dom/cjs/ReactDOM-profiling.js

@@ -7,7 +7,7 @@
  * @noflow
  * @nolint
  * @preventMunge
- * @generated SignedSource<<23caf0525b005a476914b4fd14108776>>
+ * @generated SignedSource<<5c28310e31f7b026d9838c06862fa435>>
  */
 
 "use strict";
@@ -203,4 +203,4 @@ exports.useFormState = function (action, initialState, permalink) {
 exports.useFormStatus = function () {
   return ReactSharedInternals.H.useHostTransitionStatus();
 };
-exports.version = "19.2.0-native-fb-2805f0ed-20250903";
+exports.version = "19.2.0-native-fb-3168e08f-20250903";