Remove cxx from iOS project (#25392)

Summary:
Remove cxx from iOS project, because we have the corresponding implementation in iOS. Otherwise, it would break the logical handling of iOS part.

## Changelog

[iOS] [Fixed] - Remove cxx from iOS project
Pull Request resolved: https://github.com/facebook/react-native/pull/25392

Test Plan: Fabric enabled Tester can work like loading image.

Reviewed By: mdvacca

Differential Revision: D17285463

Pulled By: shergin

fbshipit-source-id: b414406578dcce51f3b54fd06941225efc560e7f

ReactCommon/React-Fabric.podspec

@@ -165,7 +165,8 @@ Pod::Spec.new do |s|
     ss.compiler_flags       = folly_compiler_flags
     ss.source_files         = "fabric/imagemanager/**/*.{m,mm,cpp,h}"
     ss.exclude_files        = "**/tests/*",
-                              "**/android/*"
+                              "**/android/*",
+                              "**/cxx/*"
     ss.header_dir           = "react/imagemanager"
     ss.pod_target_xcconfig  = { "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/ReactCommon\" \"$(PODS_ROOT)/Folly\"" }
   end
@@ -184,7 +185,8 @@ Pod::Spec.new do |s|
     ss.compiler_flags       = folly_compiler_flags
     ss.source_files         = "fabric/textlayoutmanager/**/*.{m,mm,cpp,h}"
     ss.exclude_files        = "**/tests/*",
-                              "**/android/*"
+                              "**/android/*",
+                              "**/cxx/*"
     ss.header_dir           = "react/textlayoutmanager"
     ss.pod_target_xcconfig  = { "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/ReactCommon\" \"$(PODS_ROOT)/Folly\"" }
   end

ReactCommon/fabric/graphics/React-graphics.podspec

@@ -33,7 +33,8 @@ Pod::Spec.new do |s|
   s.compiler_flags         = folly_compiler_flags
   s.source_files           = "**/*.{m,mm,cpp,h}"
   s.exclude_files          = "**/tests/*",
-                             "**/android/*"
+                             "**/android/*",
+                             "**/cxx/*"
   s.header_dir             = "react/graphics"
   s.pod_target_xcconfig  = { "USE_HEADERMAP" => "NO", "HEADER_SEARCH_PATHS" => "\"$(PODS_TARGET_SRCROOT)/ReactCommon\" \"$(PODS_ROOT)/Folly\"" }