Update CCM post CASSANDRA-17379

We updated in CASSANDRA-15234 CCM updateconf to enable it to handle overloading of parameters Python upgrade tests. 

This also allows us not to update for 4.1 the Python DTests but exercise the backward compatibility we have in C* in our tests.

Now CASSANDRA-17379 added a few flags to opt in or out for overloading of parameters.

The default points to -Dcassandra.allow_new_old_config_keys=false but this does not affect our tests as CCM handles the overloading in the yaml.
But this is confusing for users and might lead to issues.

We need to bring on par one way or another ccm with the new flags introduced in CASSANDRA-17379

Until then the recommendation is to use `-Dcassandra.allow_new_old_config_keys=false` and  `-Dcassandra.allow_duplicate_config_keys=false` to prohibit any kind of overloading when using CCM master and CCM released to prevent any confusion.