screenshots are not available in local storage on new instance.

[brianvess]

Screenshots are not visible in documents after Importing the export of collections from S3-based storage to a new deployment that has local storage.

Steps to reproduce

1. Export all collections from outline with minio storage.
2. Deploy a fresh installation of outline with a local storage option.
3. Import export from step 1.
4. Documents are present, but no images are displayed
5. I can see images inside the pod under /var/lib/outline/data
6. I can see the images inside the docker volume.