CDK-742. Added logic to find cluster-provided Avro jars to CLI classpath

That's a good point, and it would certainly be nice to rely on a consistent packaged version of Avro. I don't remember why we decided to use the one on the cluster, and I can't seem to find the issue where we discussed it. I think it was that we don't want to have an inconsistent version due to classpath issues, but if we have to find it and manage the dependency like this then there is no downside to bundling the preferred version. That's better for parquet-avro behavior too.

I'm interested to hear what Tom has to say on this, but right now I'm thinking we should remove this entirely and bundle Avro.