Missing test resource cleanup

https://github.com/googleapis/python-pubsub/blob/eb9f233d656c4e335829f11ef8617b9af38466bb/samples/snippets/schema_test.py#L39

This test resource is never cleaned up properly after the samples tests run. 

https://github.com/googleapis/python-pubsub/blob/d8e8a31bf4f4e1866e4cc57985e15f626e6b59e9/samples/snippets/subscriber_test.py#L87

This test resource is also never cleaned up. 