fix(config): deprecated enable_file_metadata

Signed-off-by: Maxence Lange <maxence@artificial-owl.com>

config/config.sample.php

@@ -2367,17 +2367,6 @@ $CONFIG = [
  */
 'profile.enabled' => true,
 
-/**
- * Enable file metadata collection
- *
- * This is helpful for the mobile clients and will enable few optimizations in
- * the future for the preview generation.
- *
- * Note that when enabled, this data will be stored in the database and might increase
- * the database storage.
- */
-'enable_file_metadata' => true,
-
 /**
  * Allows to override the default scopes for Account data.
  * The list of overridable properties and valid values for scopes are in