RNTester: Fixes turbo module examples error in bridgeless mode (#48362)

Summary:
In #47598 , we removed `__turboModuleProxy ` in bridgeless mode, it would produce error in rntester turbomodule examples, fix it by change `__turboModuleProxy` to `nativeModuleProxy`. RSNara can you please help to review? :)

before:
![image](https://github.com/user-attachments/assets/bf8edc50-6dbc-4465-9936-36ec9112761b)

After:
![image](https://github.com/user-attachments/assets/2d5c1546-d758-4692-a9a7-5cf195edc015)

## Changelog:

[IOS] [FIXED] - RNTester: Fixes turbo module examples error in bridgeless mode

Pull Request resolved: #48362

Test Plan: RNTester turbomodule examples in bridgeless can work as expected.

Reviewed By: shwanton

Differential Revision: D67603884

Pulled By: cortinico

fbshipit-source-id: d905fa0535da5fde5e7ebff1d453ea761be9f42f

Author: zhongwuzw

packages/rn-tester/js/examples/TurboModule/NativeCxxModuleExampleExample.js

@@ -261,7 +261,7 @@ class NativeCxxModuleExampleExample extends React.Component<{}, State> {
   }
 
   componentDidMount(): void {
-    if (global.__turboModuleProxy == null && global.nativeModuleProxy == null) {
+    if (global.nativeModuleProxy == null && global.nativeModuleProxy == null) {
       throw new Error(
         'Cannot load this example because TurboModule is not configured.',
       );

packages/rn-tester/js/examples/TurboModule/SampleTurboModuleExample.js

@@ -204,7 +204,7 @@ class SampleTurboModuleExample extends React.Component<{}, State> {
   }
 
   componentDidMount(): void {
-    if (global.__turboModuleProxy == null && global.nativeModuleProxy == null) {
+    if (global.nativeModuleProxy == null && global.nativeModuleProxy == null) {
       throw new Error(
         'Cannot load this example because TurboModule is not configured.',
       );