[A11y][iOS] - VoiceOver reads first letter separately from other text in multiline textInput on legacy architecture

Description

When using TextInput component with multiline={true}, voiceover announces first symbol separately from the remaining text

Managed to reproduce on RN versions 0.73.5, 0.73.8, 0.74.2

Actual result: First symbol is read separately
Expected result: Whole text is read together

Note: The issue is not reproduced with RCT_NEW_ARCH_ENABLED = 1

Steps to reproduce

1. Turn on VoiceOver
2. Enter text
3. Tap on the input to announce

React Native Version

0.73.8

Affected Platforms

Runtime - iOS

Output of npx react-native info

System:
  OS: macOS 14.2.1
  CPU: (8) arm64 Apple M1
  Memory: 88.33 MB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 20.11.1
    path: ~/.nvm/versions/node/v20.11.1/bin/node
  Yarn:
    version: 3.6.4
    path: ~/.nvm/versions/node/v20.11.1/bin/yarn
  npm:
    version: 10.2.4
    path: ~/.nvm/versions/node/v20.11.1/bin/npm
  Watchman:
    version: 2024.01.22.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.14.3
    path: /Users/dev/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.2
      - iOS 17.2
      - macOS 14.2
      - tvOS 17.2
      - visionOS 1.0
      - watchOS 10.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2023.2 AI-232.10227.8.2321.11479570
  Xcode:
    version: 15.2/15C500b
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.10
    path: /usr/bin/javac
  Ruby:
    version: 3.3.0
    path: /Users/dev/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react: Not Found
  react-native: Not Found
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: false
iOS:
  hermesEnabled: true
  newArchEnabled: false

Stacktrace or Logs

N/A

Reproducer

https://github.com/srrmstk/react-native-multiline-a11y-reproducer

Screenshots and Videos

https://github.com/facebook/react-native/assets/61790890/5c1fa74c-1539-4d71-a56a-1af8f42fd917

リンクされている複数行アクセシビリティ再現コードから始め、iOS で legacy アーキテクチャと RCT_NEW_ARCH_ENABLED=1 の場合の VoiceOver の動作を比較します。再現に関係する legacy の TextInput パスを追跡し、影響を受ける React Native バージョンで VoiceOver が複数行の値全体をまとめて読み上げることを確認します。