Based on the general fixation on tests at Meta and Alphabet et al, it seems pretty plausible to me that they might try such a thing although:
1) the article is just the employee's claims in the context of employment arbitration, rather than evidence. For example they claim to have been shown a document about running such tests, but it's not clear whether that document has been entered into evidence (and certainly not made public). That document would presumably be subject to discovery in a lawsuit, although in arbitration it's unlikely it would be in the public record unless someone with standing made a freedom of information request (which may or may not reveal it).
2) It seems to me such a test would be unnecessary regardless of the ethics of it. You could just look at instances when a user's battery was low organically without draining it on purpose. The installed base is large enough that this would almost certainly work just as well for most practical purposes.