fix(iOS): use getNextRootViewTag() on new architecture (#51522)

Summary:
Sometime ago Fabric specific root view tag allocator was added to the codebase: 7dec625 This PR makes sure to use it on iOS. It removes the need for additional conversions.

## Changelog:

[INTERNAL] [CHANGED] -  use getNextRootViewTag() on new architecture

Pull Request resolved: #51522

Test Plan: CI Green

Reviewed By: javache

Differential Revision: D75204499

Pulled By: rshest

fbshipit-source-id: 12927887ae229c9fe89fa680f2bd55b5e378f9ae

Author: okwasniewski

packages/react-native/React/Fabric/Surface/RCTFabricSurface.mm

@@ -21,6 +21,7 @@
 #import <React/RCTSurfaceView.h>
 #import <React/RCTUIManagerUtils.h>
 #import <React/RCTUtils.h>
+#import <react/renderer/core/ReactRootViewTagGenerator.h>
 #import <react/renderer/mounting/MountingCoordinator.h>
 #import <react/utils/FollyConvert.h>
 
@@ -56,8 +57,7 @@ - (instancetype)initWithSurfacePresenter:(RCTSurfacePresenter *)surfacePresenter
   if (self = [super init]) {
     _surfacePresenter = surfacePresenter;
 
-    _surfaceHandler =
-        SurfaceHandler{RCTStringFromNSString(moduleName), (SurfaceId)[RCTAllocateRootViewTag() integerValue]};
+    _surfaceHandler = SurfaceHandler{RCTStringFromNSString(moduleName), getNextRootViewTag()};
     _surfaceHandler->setProps(convertIdToFollyDynamic(initialProperties));
 
     [_surfacePresenter registerSurface:self];