Re-enable the New Architecture by default (#48755)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/48755

When [cleaning up the pre-alpha flags](https://github.com/facebook/react-native/commit/9a4b2cecd57dc797f90280be33eb4c80a06aaf72), we disabled the new architecture by default by mistake.

This change fixes that.

## Changelog:
[Internal] - Restore the New Arch by default

Reviewed By: GijsWeterings

Differential Revision: D68323159

fbshipit-source-id: cae96fc7c50319808e0afecf46ebf927e4db254a

packages/react-native/scripts/cocoapods/new_architecture.rb

@@ -159,6 +159,6 @@ class NewArchitectureHelper
     end
 
     def self.new_arch_enabled
-        return ENV["RCT_NEW_ARCH_ENABLED"] == nil || ENV["RCT_NEW_ARCH_ENABLED"] == "1"
+        return ENV["RCT_NEW_ARCH_ENABLED"] == 0 ? false : true
     end
 end

packages/react-native/scripts/react_native_pods.rb

@@ -95,6 +95,8 @@ def use_react_native! (
 
   ReactNativePodsUtils.warn_if_not_on_arm64()
 
+  Pod::UI.puts "Configuring the target with the #{new_arch_enabled ? "New" : "Legacy"} Architecture\n"
+
   # The Pods which should be included in all projects
   pod 'FBLazyVector', :path => "#{prefix}/Libraries/FBLazyVector"
   pod 'RCTRequired', :path => "#{prefix}/Libraries/Required"