fix(performance): use low resolution for blurhash

Improve blurhash performance by using a low res image.
The results are hard to destinguish visualy.
It is a **blur** hash after all.

Signed-off-by: Max <max@nextcloud.com>

Author: max-nextcloud

lib/private/Blurhash/Listener/GenerateBlurhashMetadata.php

@@ -44,7 +44,7 @@
  * @template-implements IEventListener<AMetadataEvent>
  */
 class GenerateBlurhashMetadata implements IEventListener {
-	private const RESIZE_BOXSIZE = 300;
+	private const RESIZE_BOXSIZE = 30;
 
 	private const COMPONENTS_X = 4;
 	private const COMPONENTS_Y = 3;