Installation accounts reference their hidden app-record account by

primary key stored in JSON data rather than a database foreign key, so

nothing at the database level stops the record from being deleted out

from under them. Deleting it would silently break every installation of

the app, which authenticates using the record's stored credentials.
The django admin allows implementing a get_deleted_objects() method in

order to allow us to prevent this.
Testing Done:

Ran unit tests.

Attempted to delete the app record and saw that it was protected.
Ran unit tests.