[expo-video-thumbnails][Android] Fix memory leaks

[hirbod]

Why

1. Closing ParcelFileDescriptor properly: We were leaving the ParcelFileDescriptor open after use, which could lead to resource leaks
2. Releasing MediaMetadataRetriever after use: Previously, we weren't releasing the MediaMetadataRetriever, potentially leading to memory leaks.

How

1. I wrapped the ParcelFileDescriptor in a use block. This way, it automatically closes once we're done with it.
2. Ensuring MediaMetadataRetriever release: I added a finally block in the GetThumbnail class. This block is executed after retrieving the frame, ensuring retriever.release() is called every time, which guarantees that the resources are freed up.

Test Plan

• Emulator running SDK 33 and 34
• Real device: Google Pixel Pro 7

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for npx expo prebuild & EAS Build (eg: updated a module plugin).

[tsapeta]

Thank you! 😊