[ML] Register ML featureset in XPackClientPlugin (#53772)

Featureset needs to stay in XPackClientPlugin for now.

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackClientPlugin.java

@@ -64,6 +64,7 @@ import org.elasticsearch.xpack.core.ilm.action.PutLifecycleAction;
 import org.elasticsearch.xpack.core.ilm.action.RemoveIndexLifecyclePolicyAction;
 import org.elasticsearch.xpack.core.ilm.action.RetryAction;
 import org.elasticsearch.xpack.core.logstash.LogstashFeatureSetUsage;
+import org.elasticsearch.xpack.core.ml.MachineLearningFeatureSetUsage;
 import org.elasticsearch.xpack.core.ml.MlMetadata;
 import org.elasticsearch.xpack.core.ml.MlTasks;
 import org.elasticsearch.xpack.core.ml.action.CloseJobAction;
@@ -409,7 +410,8 @@ public class XPackClientPlugin extends Plugin implements ActionPlugin, NetworkPl
             new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.GRAPH, GraphFeatureSetUsage::new),
             // logstash
             new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.LOGSTASH, LogstashFeatureSetUsage::new),
-
+            // ML
+            new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.MACHINE_LEARNING, MachineLearningFeatureSetUsage::new),
             // monitoring
             new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.MONITORING, MonitoringFeatureSetUsage::new),
             // security

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java

@@ -60,13 +60,10 @@ import org.elasticsearch.threadpool.ScalingExecutorBuilder;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.watcher.ResourceWatcherService;
 import org.elasticsearch.xpack.core.ClientHelper;
-import org.elasticsearch.xpack.core.XPackFeatureSet;
-import org.elasticsearch.xpack.core.XPackField;
 import org.elasticsearch.xpack.core.XPackPlugin;
 import org.elasticsearch.xpack.core.XPackSettings;
 import org.elasticsearch.xpack.core.action.XPackInfoFeatureAction;
 import org.elasticsearch.xpack.core.action.XPackUsageFeatureAction;
-import org.elasticsearch.xpack.core.ml.MachineLearningFeatureSetUsage;
 import org.elasticsearch.xpack.core.ml.MachineLearningField;
 import org.elasticsearch.xpack.core.ml.MlMetaIndex;
 import org.elasticsearch.xpack.core.ml.MlMetadata;
@@ -975,8 +972,6 @@ public class MachineLearning extends Plugin implements SystemIndexPlugin, Analys
         namedWriteables.add(new NamedWriteableRegistry.Entry(PersistentTaskState.class, DatafeedState.NAME, DatafeedState::fromStream));
         namedWriteables.add(new NamedWriteableRegistry.Entry(PersistentTaskState.class, DataFrameAnalyticsTaskState.NAME,
             DataFrameAnalyticsTaskState::new));
-        namedWriteables.add(new NamedWriteableRegistry.Entry(XPackFeatureSet.Usage.class, XPackField.MACHINE_LEARNING,
-            MachineLearningFeatureSetUsage::new));
 
         namedWriteables.addAll(new MlDataFrameAnalysisNamedXContentProvider().getNamedWriteables());
         namedWriteables.addAll(MlEvaluationNamedXContentProvider.getNamedWriteables());