Issue Summary

`AttachmentService.updateData(...)` can fail with `EntityNotFoundException` after the concurrent attachment upload path changes attachment or page `ContentProperty` records in a separate transaction. The caller's transaction still holds an older Hibernate entity graph. When Confluence then refreshes that graph, Hibernate can cascade to a property row that the concurrent transaction deleted or replaced, causing the exception.
 
This affects integrations that call `AttachmentService.updateData(...)` inside their own transaction.

Steps to Reproduce

1. Create a page and attachment.
2. Add an existing `attachmentChanged-*` property to the containing page (through a plugin, or a direct database insert into CONTENTPROPERTIES).
3. In a caller-managed transaction, load the attachment container's property collection so it retains that existing property.
4. Call `AttachmentService.updateData(...)` once for the attachment.
5. The concurrent upload transaction removes/replaces the property.
6. The caller-side `refresh(container)` cascades into the deleted property and throws `EntityNotFoundException`.

Expected Results

The attachment data is updated with the data provided to `updateData`

Actual Results

The `EntityNotFoundException` is raised and the transaction rolls back.

The below exception is thrown in the logs:

jakarta.persistence.EntityNotFoundException: No row with the given identifier exists: [com.atlassian.confluence.content.ContentProperty#564330559]
...
    at jdk.proxy4/jdk.proxy4.$Proxy266.refresh(Unknown Source)
    at com.atlassian.confluence.api.impl.service.content.AttachmentServiceImpl.updateAttachmentData(AttachmentServiceImpl.java:485)
    at com.atlassian.confluence.api.impl.service.content.AttachmentServiceImpl.updateData(AttachmentServiceImpl.java:316) 

Workaround

The following sysprop can be enabled on instances (>=9.2.22 or >=10.2.14) to avoid uploading attachments in a separate transaction when calling updateData (preventing the calling transaction from going out of sync):

-Dconfluence.attachment.upload.concurrency.guard.disabled=true