Temporary attachments not clearing automatically (tmp_attachments)

Issue Summary

The issue is that the temporary attachments located in <Jira home>/caches/tmp_attachments are not clearing or being deleted.  

Steps to Reproduce

1. Create or Edit Issues 
2. Add an attachment to the issue 
3. Cancel creating or editing the issue after adding the attachment

NOTE: This will create a temp file located in <Jira home>/caches/tmp_attachments.

Expected Results

The expectation is that these temp files would be cleared or deleted automatically after canceling the issue. The reason for this expectation is that when you create an issue or edit an issue with an attachment the file is created and removed automatically. 

According to documentation DefaultTemporaryWebAttachmentsMonitor, the job should be clearing these tmp files automatically. 

This class maintains a list of temporary attachments uploaded by a user. When the user's session expires or the user logs out, it is responsible of deleting any temporary files that were not converted to proper attachments.

Since:
6.4

Actual Results

When canceling an issue that you are editing or creating with an attachment the temp file is not removed automatically. When logging out from the user it does not remove the temp file. 

Workaround

There are currently two workarounds for this issue that should delete these files.

• Removing the files manually or through a task from <Jira home>/caches/tmp_attachments
• Attempting to stop the Jira instance which should clear the tmp_attachment folder completely.
  • Stop the Jira instance
  • Confirm that tmp_attachment folder has been deleted located in<Jira home>/caches/
  • Start the Jira instance (This should create again the tmp_attachment folder)