Deleted userdata owned by a deleted account remains linked with the template

##### ISSUE TYPE

* Bug Report

##### COMPONENT NAME

~~~
Server
~~~

##### CLOUDSTACK VERSION

~~~
4.19 branch, most likely earlier versions
~~~

##### CONFIGURATION

NA

##### OS / ENVIRONMENT

NA

##### SUMMARY

Deleted userdata owned by a deleted account remains linked with the template. In UI it produces a 404 error. During VM deployment with the linked template it return error like,
`UserData linked to the template CentOS 5.6(64-bit) no GUI (XenServer) is not found`

##### STEPS TO REPRODUCE

~~~
1. As the admin, create a new user account
2. As the new user, register a userdata
3. As the admin, link the userdata to a template
4. As the admin, delete the new user
5. Observer userdata remains linked to the template
~~~

https://github.com/user-attachments/assets/7e97ae35-0875-4152-aaa0-1dab44e2148f

##### EXPECTED RESULTS

~~~
Maybe either an error while deleting the user account or the userdata that gets deleted is unlinked from the template
~~~

##### ACTUAL RESULTS

~~~
Delete userdata remains linked to the template
~~~