Inline true for fabricEnabled in DefaultNewArchitectureEntryPoint (#56882)

Summary:
Pull Request resolved: #56882

Now that `fabricEnabled` always returns `true`, delete the `privateFabricEnabled` backing field. Remove the redundant assignment in `load()` and inline `true` at its remaining usage in `isConfigurationValid` from `loadWithFeatureFlags`.

Behavior is unchanged.

Changelog:
[Internal]

Reviewed By: alanleedev, fkgozali

Differential Revision: D105639307

fbshipit-source-id: 0c229ece1b50965cf9b6dcf8ec744d5373f8a91d

Author: mdvacca

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/defaults/DefaultNewArchitectureEntryPoint.kt

@@ -102,7 +102,6 @@ public object DefaultNewArchitectureEntryPoint {
       }
     }
 
-    privateFabricEnabled = fabricEnabled
     privateTurboModulesEnabled = turboModulesEnabled
     privateConcurrentReactEnabled = fabricEnabled
     privateBridgelessEnabled = bridgelessEnabled
@@ -120,7 +119,7 @@ public object DefaultNewArchitectureEntryPoint {
     val (isValid, errorMessage) =
         isConfigurationValid(
             privateTurboModulesEnabled,
-            privateFabricEnabled,
+            true,
             privateBridgelessEnabled,
         )
     if (!isValid) {
@@ -130,8 +129,6 @@ public object DefaultNewArchitectureEntryPoint {
     DefaultSoLoader.maybeLoadSoLibrary()
   }
 
-  private var privateFabricEnabled: Boolean = false
-
   @JvmStatic
   public val fabricEnabled: Boolean
     get() = true