Blueprints don't support cluster creation when using existing DB

When deploying a cluster via a blueprint where the MYSQL_SERVER component is not included in the topology but instead already exists, a 400 response is returned to the user even if the user properly configured the necessary configurations for an existing server.

{
"status" : 400, "message" : "Unable to update configuration properties with topology information. Component 'MYSQL_SERVER' is not mapped to any host group or is mapped to multiple groups."
}

This occurs when deploying the cluster when the configurations are updated with topology related information. For components that may be external, we need to check if the user updated the default hostname or port in the corresponding configuration and if they have, don't do any topology update on the property.