Replace the usage of "graph-name" by the native protocol's keyspace

From JAVA-1112:

With DSP-8793, DSE is going to use the keyspace from the native protocol options and not use the "graph-name" key of the custom payload, to determine the graph name since a graph is now closely tied to a keyspace. So we can now re-use the driver's keyspace native protocol instead of using the custom payload option.