fix: close bucketed cluster config model gaps

src/cluster/cluster.rs

@@ -37,8 +37,9 @@ pub struct Cluster {
 
 impl Cluster {
     pub fn new(config: &Config, model: &ModelConfig) -> Self {
-        let mut instances = Vec::with_capacity(config.cluster.num_instances as usize);
-        for id in 0..config.cluster.num_instances {
+        let total_instances = config.cluster.total_instances();
+        let mut instances = Vec::with_capacity(total_instances as usize);
+        for id in 0..total_instances {
             instances.push(Instance::new(
                 id as InstanceId,
                 model,
@@ -226,7 +227,9 @@ mod tests {
                 ..CalibrationConfig::default()
             },
             cluster: ClusterConfig {
-                num_instances: 1,
+                num_instances: Some(1),
+                buckets: Vec::new(),
+                global_router: Default::default(),
                 meta_store: MetaStoreConfig {
                     ttl_seconds: 1000.0,
                 },