Disabling Collaborative Editing feature does not remove existing shared drafts

Summary

As per the Administering Collaborative Editing documentation, all existing shared drafts should be deleted upon disabling the Collaborative Editing feature.

All existing shared drafts are lost when you switch to this mode, so make sure your users have published any work they want to keep before you make the change.

How to Reproduce

1. Enable Collaborative Editing.
2. Create a shared draft by inserting some texts on the title and the content space.
3. Quit editing by closing the browser tab or save the draft by clicking the 'Close' button at the bottom right of the editor and choose 'Keep Draft'.
4. Disable and reenable Collaborative Editing.

Expected Behavior

Existing shared drafts should be deleted from the database.

Actual Behavior

Existing shared drafts remain in the database. The following SQL query returns result(s).

SELECT * FROM CONTENT WHERE CONTENTTYPE = 'PAGE' AND CONTENT_STATUS = 'draft';

Workaround

1. Discard the drafts via Profile Picture > Drafts.
   Reference: https://confluence.atlassian.com/doc/drafts-149040.html#Drafts-deleteDeleteadraft
2. Remove all drafts from the database using the following SQL query.

   DELETE FROM CONTENT WHERE CONTENTTYPE = 'PAGE' AND CONTENT_STATUS = 'draft';

   It is important that you backup your data before performing any modifications to the database. Please test any INSERT, UPDATE or DELETE queries on a staging environment prior to rolling out changes onto production environment.