Remote video thumbnail is not replaced when updating metadata (needs FileExists::Replace support)

Problem/Motivation

I am trying to give editors the ability to refresh remote video metadata (including thumbnails) when using the Video Embed Field module.

I applied the patch from Drupal core issue:
https://www.drupal.org/project/drupal/issues/2983456

This exposes the "Update metadata" functionality for media entities. However, even after updating metadata, the thumbnail image is not replaced.

The problem is not with Vimeo or oEmbed — the JSON endpoint returns the correct, updated thumbnail URL.

After clicking "Update metadata", the thumbnail file stored locally at:

public://video_thumbnails/{video_id}.jpg

remains unchanged.

The issue appears to be that the existing thumbnail file is not replaced when it already exists locally. Since Vimeo uses a stable filename based on the video ID, the filename does not change, and the file system does not overwrite the existing file.

As a result, editors cannot refresh thumbnails even though the provider returns updated metadata.

Steps to reproduce

1. Create a Remote Video media item using Video Embed Field (e.g., Vimeo).
2. Confirm that the thumbnail is downloaded locally to:
   

   public://video_thumbnails/{video_id}.jpg

3. Change the thumbnail in Vimeo.
4. Verify that the Vimeo oEmbed endpoint returns the updated thumbnail_url.
5. Click "Update metadata" in Drupal.
6. Observe that the local thumbnail file is not replaced and the old thumbnail remains visible.

Proposed resolution

When updating metadata, the thumbnail download process should replace the existing file if the remote thumbnail URL has changed.

This can be achieved by using:

use Drupal\Core\File\FileExists;

$this->fileSystem->saveData(
  $data,
  $destination,
  FileExists::Replace
);