Issue Summary

"Create sub-task" option available on Epic and the above issuetype hierarchy

Steps to Reproduce

1. In this example: ('Technical Story' Level 2 issuetype hierarchy )
   Issue type hierarchy:
   

1. 1Jira project has only two issuetypes Level2 (basically it could be Level1 or above) and subtasks:
   

1. 2Create Jira ticket with Level2 and it shows 'Create subtask" option
   
2. The same is applied to 'Epic' with Subtask only
   
3. Another possibility:
   If a project has Skip level issuetype hierarchy (eg Level3 , Level1 and Level -1) configured. The project is affected by this Bug to show 'Create Subtask'
   This means consecutive levels are not present to establish Parent-Child relations. 

Expected Results

Hide/remove the "Create sub-task"  button from the issue view when the issue type is configured above an Epic in the Issue type hierarchy and prevent users from creating subtasks in such issue types (Level2 and above)

Actual Results

When an issue type is configured in the Issue type hierarchy above an Epic (or Level2/3 etc) and subtask, it still shows the option to "Create a sub-task".

Workaround

Avoid creating Jira projects having only Issuetypes Level 2 & above with subtasks.