This is a follow-up to a sequence of earlier posts. The posts have been closed because they did not meet the moderator's expectations. I have new information, and I'm re-posting so that I can answer my own question.
Why is my unpublished app being run remotely? stated that I had modified my app to "phone home" whenever it was being run in debug mode on a device I don't recognize. I received messages indicating the my unpublished code was being run on a server far away. Spyware detected - what to do about it stated that a factory reset on my Android test device prevented the remote reports from happening.
It turns out that the factory reset wasn't sufficient. Once I re-installed my usual software on my Android test devices, the remote reports returned.