Tried using port 54321 for Flow proxy, but port was already occupied

I've a Spark application with dependencies on H2O Sparkling Water jars

```
// H2O Sparkling Water version (spark 2.4)
val h2oVersion = "3.32.0.1-2-2.4"
lazy val h2oLibs = Seq(
"org.apache.spark" %% "spark-repl" % sparkVersion,
"ai.h2o" % "sparkling-water-package_2.11" % h2oVersion //exclude("ai.h2o", "sparkling-water-api-generation")
)
```
When I try to start it on k8s, the Spark executor starts properly (see logs from executor container below) and I can open a port-forward connection to it and access flow UI.
But the driver node gets stack in infinity loop and I see in the logs the following
```
2020-12-03T17:04:59.532+0000 level=INFO thread=main logger=ai.h2o.sparkling.backend.utils.RestApiUtils
H2O node http://10.1.0.22:54321/3/verifyWebOpen successfully responded for the GET.
2020-12-03T17:04:59.553+0000 level=INFO thread=main logger=ai.h2o.sparkling.backend.utils.RestApiUtils
H2O node http://10.1.0.22:54321/3/verifyVersion?referenced_version=3.32.0.1 successfully responded for the GET.
2020-12-03T17:04:59.636+0000 level=INFO thread=main logger=ai.h2o.sparkling.backend.utils.RestApiUtils
H2O node http://10.1.0.22:54321/3/Cloud successfully responded for the GET.
2020-12-03T17:04:59.713+0000 level=INFO thread=main logger=ai.h2o.sparkling.backend.utils.RestApiUtils
H2O node http://10.1.0.22:54321/3/LogLevel successfully responded for the GET.
2020-12-03T17:04:59.951+0000 level=INFO thread=main logger=ai.h2o.sparkling.backend.utils.RestApiUtils
H2O node http://10.1.0.22:54321/99/Rapids successfully responded for the POST.
2020-12-03T17:05:00.011+0000 level=WARN thread=main logger=ai.h2o.sparkling.backend.utils.ProxyStarter
Tried using port 54321 for Flow proxy, but port was already occupied!
```

Apparently, when SW tries to check for available ports it uses the Spark driver host but later jetty server binds to 0.0.0.0

See here for detailed discussion https://github.com/h2oai/sparkling-water/issues/2414