Enable metrics endpoint for older versions of Cassandra

[emerkle826]

In the initial implementation, we disabled the new metrics endpoint for some older versions of Cassandra due to some library conflicts. Once #426 is implemented, we should be able to remove the metrics endpoint limitations as there should no longer be library conflicts. (See code here: https://github.com/k8ssandra/management-api-for-apache-cassandra/blob/master/management-api-agent-common/src/main/java/io/k8ssandra/metrics/interceptors/MetricsInterceptor.java#L43-L59)

┆Issue is synchronized with this Jira Story by Unito
┆Issue Number: MAPI-18