Discovered by lsansone while testing MDLQA-19052

When backing up and restoring activities and resources, replacing the sources in private and course legacy files with new versions does not update the file references after restoration. Instead, the restored files continue to point to the old versions, failing to link to the newly replaced files.

Steps to reproduce

1. Add several files to your private files area, including images.
2. Create an activity module, insert into the description images from previous step as alias/shortcuts by selecting Link to the file.
3. Create a new folder resource and add the same files from as alias/shortcuts by selecting Link to the file.
4. Backup the activities and resources created.
5. Replace sources in private files
6. Restore activities/resources from the backup.

Expected Result: The restored activities and resources should reference the newly uploaded files, ensuring that the files are present and valid.

Actual Result: The restored files continue to reference the old versions, leading to incorrect file associations.