fix(server): don't reimport files more than once (#16375)

* fix(server) don't reimport files more than once

* fix: test

---------

Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

server/src/services/metadata.service.ts

@@ -248,7 +248,7 @@ export class MetadataService extends BaseService {
       duration: exifTags.Duration?.toString() ?? null,
       localDateTime,
       fileCreatedAt: exifData.dateTimeOriginal ?? undefined,
-      fileModifiedAt: exifData.modifyDate ?? undefined,
+      fileModifiedAt: stats.mtime,
     });
 
     await this.assetRepository.upsertJobStatus({