Downgrade Scala version in Spark job-server to prevent Scala serialization bug

[mosche]

Downgrade the Scala version of the job-server to match the Scala version of a Spark 3.1.2 cluster to prevent
a Scala bug (InvalidClassException when deserializing WrappedArray)

(fixes #21092)

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[mosche]

R: @aromanenko-dev
R: @ibzib

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[mosche]

@aromanenko-dev ping, should be quick to review ... just a small change to force the right Scala version

[aromanenko-dev]

Run Python Spark ValidatesRunner

[mosche]

@aromanenko-dev Unfortunately there's no tests that would cover this ... such classpath issues can only be detected if NOT running Spark in local mode.

I just noticed that the Spark 2 job-server / runner is broken as well, what a mess 😭 😡

java.lang.NoSuchMethodError: com.fasterxml.jackson.databind.type.TypeBindings.emptyBindings()Lcom/fasterxml/jackson/databind/type/TypeBindings;
	at org.apache.beam.sdk.options.PipelineOptionsFactory.createBeanProperty(PipelineOptionsFactory.java:1708)
	at org.apache.beam.sdk.options.PipelineOptionsFactory.computeDeserializerForMethod(PipelineOptionsFactory.java:1732)
	at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)
	at org.apache.beam.sdk.options.PipelineOptionsFactory.getDeserializerForMethod(PipelineOptionsFactory.java:1782)
	at org.apache.beam.sdk.options.PipelineOptionsFactory.deserializeNode(PipelineOptionsFactory.java:1806)

That issue is even worse, I'm pretty convinced this isn't only affecting the portable runner. Attempting to deserialize pipeline options will fail on the cluster using either PortableRunner or SparkRunner because the expected Jackson API is newer than the one available on the Spark cluster

[aromanenko-dev]

@mosche Do we still support Spark 2 runner? I believed it was deprecated and finally will be dropped out.

[mosche]

Yes, we deprecated it ... but apparently it cannot be used anymore since long.

[aromanenko-dev]

LGTM, sorry for delay