Issue Summary

Currently it's possible to split a backup file to import it, importing the media data after the xml files are imported

https://support.atlassian.com/atlassian-cloud/kb/partial-or-selective-import-of-a-jira-backup-export-into-jira-cloud/

This produces and error "Preview unavailable" error in description/comments after media import.

Steps to Reproduce

1. Split a backup file as per https://support.atlassian.com/atlassian-cloud/kb/partial-or-selective-import-of-a-jira-backup-export-into-jira-cloud/
2. Import the XML files 
3. Import media data

Expected Results

description/comments should show the correct previews

Actual Results

Workaround

Visit the GET work item REST API endpoint for the affected work items. and then reload the work item

For example:

https://<instance>.atlassian.net/rest/api/3/issue/KEY-123 

then 

https://<instance>.atlassian.net/browse/KEY-123 

For comments:

https://<instance>.atlassian.net/rest/api/3/issue/KEY-123/comment

then 

https://<instance>.atlassian.net/browse/KEY-123