Some cluster tests use `cluster_con` when they need a different load
balancing policy or auth provider. However, no test uses a port
other than 9042 or enables SSL, but all tests must pass `9042, False`
because these parameters don't have default values. This makes the code
more verbose. Also, it's quite obvious that 9042 stands for port, but
it's not obvious what `False` is related to, so there is a need to check
the definition of `cluster_con` while reading any test that uses it.
No reason to backport, it's only a minor refactoring.
Closesscylladb/scylladb#25516
We simply assign the nodes used in the test to seprate racks to
ensure that the created keyspace is RF-rack-valid to be able
to run the test with the `rf_rack_valid_keyspaces` configuration
option set to true. The change does not affect what the test
does and verifies -- it only depends on the type of nodes,
whether they are normal token owners or not -- and so the changes
are correct in that sense.