Remove protocol v5 beta status

CASSANDRA-14973 is ready to be merged.

When this ticket lands server-side, we need to remove the beta status of protocol v5 driver-side.

We also need to investigate whether or not a connection with v5 is possible if there is a mismatch between driver and server regarding the beta status of this protocol. If a connection is not possible, we should also instruct users to upgrade to this driver version if they want to use protocol v5 with C* 4.0.