Repository: flutter
Issue: Lost image assets from downloaded deferred component on release build
Labels: platform-android,engine,a: release,has reproducible steps,P2,found in release: 2.2,found in release: 2.4,found in release: 2.5,team-android,triaged-android

## Steps to Reproduce

I follow [this document](https://flutter.dev/docs/perf/deferred-components) to implement deferred component and it works on my devices on debug.
When I build a release, I got the issue with image asset - it couldn't load images from the downloaded component after I install another component

1. Have 2 components: `images`, `audios`
2. On the first screen, download `images`. Once the progress completes, display those image in `Image.asset` or load by `rootBundle.load()`. In this step, the images are showing correctly
3. Navigate to another screen and download `audios` component & wait for it to complete.
4. Back to the first screen, all the images aren't accessible, it says `unable to load asset`
5. Kill the app & reopen, the image assets are working correctly again
6. This error only happen on release build with `flutter build appbundle`

**Expected results:** <!-- what did you want to see? -->
The downloaded image assets should be always accessible
**Actual results:** <!-- what did you see? -->
The image asset are gone, and it throws error. And **this only happens on release build**
When I read the engine source code, I guest the issue is coming from the flutter asset context [here](https://github.com/flutter/engine/blob/master/shell/platform/android/io/flutter/embedding/engine/deferredcomponents/PlayStoreDeferredComponentManager.java#L390). For some reason it can't load the AssetManager from flutter engine on downloaded component 
I think I would need a way to call  `loadAssets()` method to reload the context after I download the second component
<details>
  <summary>Logs</summary>



```console
[✓] Flutter (Channel master, 2.4.0-5.0.pre.122, on Mac OS X 10.15.7 19H1217 darwin-x64, locale en-US)
    • Flutter version 2.4.0-5.0.pre.122 at /Users/admin/Documents/Soft/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 5acf7e98f1 (2 days ago), 2021-07-20 19:58:58 -0700
    • Engine revision 9b270621e4
    • Dart version 2.14.0 (build 2.14.0-338.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/admin/Library/Android/sdk
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Users/admin/Library/Android/sdk
    • ANDROID_SDK_ROOT = /Users/admin/Library/Android/sdk
    • Java binary at: /Applications/Android Studio 4.2 Preview.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6916264)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.4, Build version 12D4e
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.2)
    • Android Studio at /Applications/Android Studio 4.2 Preview.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.8+10-b944.6916264)

[✓] VS Code (version 1.58.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.24.0

[✓] VS Code (version 1.59.0-insider)
    • VS Code at /Applications/Visual Studio Code - Insiders.app/Contents
    • Flutter extension version 3.24.0

[✓] Connected device (3 available)
    • SM T295 (mobile) • R9WR300R6QJ • android-arm64  • Android 10 (API 29)
    • macOS (desktop)  • macos       • darwin-x64     • Mac OS X 10.15.7 19H1217 darwin-x64
    • Chrome (web)     • chrome      • web-javascript • Google Chrome 92.0.4515.107
    ! Error: z's iPhone is not connected. Xcode will continue when duc’s iPhone is connected. (code -13)

• No issues found!
```

</details>