EC: SCM unregistered event handler for DatanodeCommandCountUpdated

In SCM I see logs like:

2023-01-04 23:56:45,346 WARN org.apache.hadoop.hdds.server.events.EventQueue: No event handler registered for event TypedEvent{payloadType=DatanodeDetails, name='Datanode_Command_Queue_Updated'}

It seems an event handler was not registered correctly for the new events which are getting produced, which causes noise in the logs and perhaps the messages to build up in the queue and may result in memory issues.

This event was created to notify RM when the queue is updated via a heartbeat so it can adjust replication load limits. The handler `DatanodeCommandCountUpdatedHandler` was for this purpose, but perhaps it is not wired up correctly.