Update FPC invoker health reporting logic (#5464)

* update FPC invoker health logic

* fix scalafmt

---------

Co-authored-by: Brendan Doyle <brendand@qualtrics.com>

core/controller/src/main/scala/org/apache/openwhisk/core/loadBalancer/FPCPoolBalancer.scala

@@ -627,7 +627,10 @@ class FPCPoolBalancer(config: WhiskConfig,
  val missingHealths =
  if (healthsFromEtcd.isEmpty) Set.empty[InvokerHealth]
  else
- ((0 to healthsFromEtcd.maxBy(_.id.toInt).id.toInt).toSet -- healthsFromEtcd.map(_.id.toInt))
+ ((healthsFromEtcd
+ .minBy(_.id.toInt)
+ .id
+ .toInt to healthsFromEtcd.maxBy(_.id.toInt).id.toInt).toSet -- healthsFromEtcd.map(_.id.toInt))
  .map(id => new InvokerHealth(InvokerInstanceId(id, Some(id.toString), userMemory = 0 MB), Offline))
  (healthsFromEtcd ++ missingHealths) sortBy (_.id.toInt)
  }