Rewrite Future.{onFailure, onSuccess} in a select chain

[MasseGuillaume]

a.b.c.onFailure{ x => y }

seen in:

https://github.com/akka/akka/blob/d01487778652d92bfe1edbf1eb7c53b4de04a2b0/akka-remote-tests/src/multi-jvm/scala/akka/remote/artery/aeron/AeronStreamConcistencySpec.scala#L123-L141