API to find zones for a resource doesn't handle deleted service

Consider the following steps:

1. Create a service named dev_hive of type hive
2. Create a security-zone named zone-sales, containing sales database from dev_hive service.
3. Call REST API to find security-zones for sales database: service/public/v2/api/zone-names/dev_hive/resource?resource:database=sales
4. Above call returns ["zone-sales"]
5. Delete service dev_hive
6. Call the same REST API from step #3

Expected result: since service has been deleted, this API should return an empty value.

Actual result: the API continues to return ["zone-sales"]