Delete enableFabricRenderer() from ReactNativeNewArchitectureFeatureFlags (facebook#56860)

Summary:

The `enableFabricRenderer()` flag is being removed entirely; it was always set to true in the canary release stage. All callers of `ReactNativeNewArchitectureFeatureFlags.enableFabricRenderer()` were inlined in earlier diffs.

This diff:
- Removes the wrapper method `ReactNativeNewArchitectureFeatureFlags.enableFabricRenderer()`.
- Removes the `override fun enableFabricRenderer(): Boolean = true` from `ReactNativeNewArchitectureFeatureFlagsDefaults`.

Both classes are non-`generated`, so they are edited directly. The next diff will remove the underlying `ReactNativeFeatureFlags.enableFabricRenderer()` API by regenerating the codegen output.

Behavior is unchanged.

Changelog:
[Internal]

Reviewed By: javache

Differential Revision: D105231777

Author: mdvacca

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeNewArchitectureFeatureFlags.kt

@@ -35,18 +35,6 @@ public object ReactNativeNewArchitectureFeatureFlags {
     return ReactNativeFeatureFlags.enableBridgelessArchitecture()
   }
 
-  @JvmStatic
-  public fun enableFabricRenderer(): Boolean {
-    if (ReactBuildConfig.UNSTABLE_ENABLE_MINIFY_LEGACY_ARCHITECTURE) {
-      Assertions.assertCondition(
-          ReactNativeFeatureFlags.enableFabricRenderer(),
-          "ReactNativeFeatureFlags.enableFabricRenderer() should be set to TRUE when Strict Mode is enabled",
-      )
-      return true
-    }
-    return ReactNativeFeatureFlags.enableFabricRenderer()
-  }
-
   @JvmStatic
   public fun useFabricInterop(): Boolean {
     if (ReactBuildConfig.UNSTABLE_ENABLE_MINIFY_LEGACY_ARCHITECTURE) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeNewArchitectureFeatureFlagsDefaults.kt

@@ -25,8 +25,6 @@ public open class ReactNativeNewArchitectureFeatureFlagsDefaults() :
 
   override fun enableBridgelessArchitecture(): Boolean = true
 
-  override fun enableFabricRenderer(): Boolean = true
-
   override fun useNativeViewConfigsInBridgelessMode(): Boolean = true
 
   override fun useTurboModuleInterop(): Boolean = true