chore(openmetrics): export only "real" files count

Other files like files in trashbin or file versions should be exported
by related app

Signed-off-by: Benjamin Gaussorgues <benjamin.gaussorgues@nextcloud.com>

lib/private/OpenMetrics/Exporters/FilesByType.php

@@ -61,6 +61,7 @@ class FilesByType extends Cached {
 		$qb = $this->connection->getQueryBuilder()->runAcrossAllShards();
 		$metrics = $qb->select('mimetype', $qb->func()->count('*', 'count'))
 			->from('filecache')
+			->where($qb->expr()->like('path', $qb->createNamedParameter('files/%')))
 			->groupBy('mimetype')
 			->executeQuery();