[Android Deployment Docs] Clean up outdated sections, legacy embedder references, and duplicate command

The [Build and release an Android app](https://docs.flutter.dev/deployment/android) page contains several stale sections and minor errors that need cleanup:

1. **Legacy Multidex section:** Mentions targeting API < 20, which Flutter no longer supports, and contains outdated CLI/IDE screenshots.
2. **Outdated Android Studio screenshots:** The Build Variants and Gradle module screenshots show the legacy Android Studio UI from several versions ago.
3. **Garbled command in FAQ:** The command in the FAQ has duplicated arguments: `apkanalyzer files list --files-only files list --files-only `.
4. **v1 Embedder FAQ item:** Recommends checking for `flutterEmbedding="1"`, which is obsolete since v1 embedders were removed in Flutter 3.22.
5. **Java 9 reference:** Notes that `-storetype JKS` is required for "Java 9+", whereas Java 17/21 is the standard for modern Android development.
6. **Third-party tools:** Mentions third-party community tools ("Flutter Shark" / "Flutter Hunt") in the FAQ that should be reviewed for currency.