Deleting User is not deleting the User data in the APP_USER table

Steps to Reproduce:

1. Create a new User with username "ABCDE" via JIRA User Management page.
2. After the user created, run these SQL query to check the user details in the database:

   select * from cwd_user where lower_user_name = 'abcde';
   select * from app_user where lower_user_name = 'abcde';
   

3. The user details will be appearing for both queries.
4. Delete the user via JIRA and run the same query.

Expected Results:
The user Row will be deleted from both tables.

Actual Results:
The user data still exist in APP_USER table.

Note:
If the user is not being deleted in the APP_USER table, would it not take any history or issue link if there is another user with the same name created in the future.