Do not load Flipper via reflection (#34383)

Summary:
Followup to https://github.com/facebook/react-native/issues/34379 by danilobuerger

Loading Flipper via reflection is type unsafe and requires extra code + exception handling that we can get rid of. The recommended way to use Flipper on Android is either via a `no-op` artifact or by using build flavors.

As we already had a setup for Flipper for `debug`, I'm creating the `release` equivalent which is just a stub. This allows us to get rid of some code inside `MainApplication.java`

## Changelog

[Android] [Changed] - Do not load Flipper via reflection

Pull Request resolved: https://github.com/facebook/react-native/pull/34383

Test Plan: Will wait for a CI result on this.

Reviewed By: cipolleschi

Differential Revision: D38615257

Pulled By: cortinico

fbshipit-source-id: 66bb2c46c5df36a15c1b27512209a849f55d64c9

template/android/app/src/debug/java/com/helloworld/ReactNativeFlipper.java

@@ -25,6 +25,10 @@ import com.facebook.react.bridge.ReactContext;
 import com.facebook.react.modules.network.NetworkingModule;
 import okhttp3.OkHttpClient;
 
+/**
+ * Class responsible of loading Flipper inside your React Native application. This is the debug
+ * flavor of it. Here you can add your own plugins and customize the Flipper setup.
+ */
 public class ReactNativeFlipper {
   public static void initializeFlipper(Context context, ReactInstanceManager reactInstanceManager) {
     if (FlipperUtils.shouldEnableFlipper(context)) {