HubSpec has intermittent test failure

[pjfanning]

https://github.com/apache/pekko/actions/runs/25488655640/job/74790703333

[05-07 10:11:25.353] [info] - must ensure that subsequent consumers see subsequent elements without gap *** FAILED *** (34 milliseconds)
[05-07 10:11:25.353] [info]   Vector(9, 10, 11, 12, 13, 14, 15, 16, 17, 18) did not equal Range$Inclusive(11, 12, 13, 14, 15, 16, 17, 18, 19, 20) (HubSpec.scala:406)
[05-07 10:11:25.353] [info]   org.scalatest.exceptions.TestFailedException:
[05-07 10:11:25.353] [info]   at org.scalatest.matchers.MatchersHelper$.indicateFailure(MatchersHelper.scala:392)
[05-07 10:11:25.353] [info]   at org.scalatest.matchers.should.Matchers$AnyShouldWrapper.should(Matchers.scala:7469)
[05-07 10:11:25.353] [info]   at org.apache.pekko.stream.scaladsl.HubSpec.$anonfun$new$38(HubSpec.scala:406)
[05-07 10:11:25.353] [info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[05-07 10:11:25.353] [info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[05-07 10:11:25.353] [info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[05-07 10:11:25.353] [info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[05-07 10:11:25.353] [info]   at org.scalatest.Transformer.apply(Transformer.scala:20)
[05-07 10:11:25.353] [info]   at org.scalatest.wordspec.AnyWordSpecLike$$anon$3.apply(AnyWordSpecLike.scala:1240)
[05-07 10:11:25.353] [info]   at org.apache.pekko.stream.testkit.StreamSpec.withFixture(StreamSpec.scala:66)
[05-07 10:11:25.353] [info]   at org.scalatest.wordspec.AnyWordSpecLike.invokeWithFixture$1(AnyWordSpecLike.scala:1238)
[05-07 10:11:25.353] [info]   at org.scalatest.wordspec.AnyWordSpecLike.$anonfun$runTest$1(AnyWordSpecLike.scala:1250)
[05-07 10:11:25.353] [info]   at org.scalatest.SuperEngine.runTestImpl(Engine.scala:306)
[05-07 10:11:25.353] [info]   at org.scalatest.wordspec.AnyWordSpecLike.runTest(AnyWordSpecLike.scala:1250)
[05-07 10:11:25.353] [info]   at org.scalatest.wordspec.AnyWordSpecLike.runTest$(AnyWordSpecLike.scala:1232)
[05-07 10:11:25.353] [info]   at org.apache.pekko.testkit.PekkoSpec.runTest(PekkoSpec.scala:82)