fix: don't persist previews used during blurhash generation

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

lib/private/Blurhash/Listener/GenerateBlurhashMetadata.php

@@ -67,23 +67,11 @@ public function handle(Event $event): void {
 			return;
 		}
 
-		$image = false;
-		try {
-			// using preview image to generate the blurhash
-			$preview = $this->preview->getPreview($file, 256, 256);
-			$image = @imagecreatefromstring($preview->getContent());
-		} catch (NotFoundException $e) {
-			// https://github.com/nextcloud/server/blob/9d70fd3e64b60a316a03fb2b237891380c310c58/lib/private/legacy/OC_Image.php#L668
-			// The preview system can fail on huge picture, in that case we use our own image resizer.
-			if (str_starts_with($file->getMimetype(), 'image/')) {
-				$image = $this->resizedImageFromFile($file);
-			}
-		}
-
-		if ($image === false) {
+		if (!str_starts_with($file->getMimetype(), 'image/')) {
 			return;
 		}
 
+		$image = $this->resizedImageFromFile($file);
 		$metadata->setString('blurhash', $this->generateBlurHash($image))
 				 ->setEtag('blurhash', $currentEtag);
 	}