IMPALA-5162, or in tandem with, enhance concurrent_select.py to run against Impala with SSL support. Make sure any bitrotted Kerberos-related code gets working again.
Much of the work here goes into the tests.comparison.cluster and db_connection abstractions, also part of
IMPALA-5162. The focus here is on the concurrent_select.py entry point. We'll need to set options to connect to Impala in a slightly different way when using Kerberos+SSL.