Delete cascade connection profiles when deleting user/organization

[PavelJankoski]

Summary

The connection profiles are not deleted when the user/organization that created them is deleted.

Steps to Reproduce

1. Create user.
2. Create wifi/ethernet profile with that user.
3. Delete the user.
4. Create user with the same user-id.
5. Fetch profiles for that user.

Current Result

The previously created profiles are there.

Expected Result

Profiles should be empty for that user-id.

Deployment

The Things Stack Open Source (self-hosted)

Contributing

• I can help by doing more research.
• I can help by implementing a fix after the proposal above is approved.
• I can help by testing the fix before it's released.

Validation

• The fix is tested in a staging environment.
• The fix is documented in The Things Stack Documentation

Code of Conduct

• I agree to follow TTN's Community Code of Conduct.