Need to clean up Pub/Sub topic resources during tests

[anguillanneuf]

Using this issue to track how many topics are created but not cleaned up by the samples tests in

python-logging/samples/snippets/usage_guide.py

Line 253 in bce6741

topic_id = "sink-pubsub-%d" % (_millis(),)

Note that there's a hard limit of 10,000 Pub/Sub topics per project.

[daniel-sanche]

Good catch, I opened #324 to address this. Let me know if you see any other resources that aren't being cleaned up properly