=str #15622 ActorPublisher now has subscriptionTimeout support

True, so I tried improve this test by choosing a larger timeout (500ms) and use a `within(2 * timeout)` block to wrap the expectNoMsg. Still timing sensitive though, yes - do you think it's worth it to add Debug events to the eventstream to make this one not timing sensitive (can do so, just didn't see many of such uses in current codebase)?