Add missing scope to explain, clear cache and field usage API (elastic#97632)

Author: javanna

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestClearIndicesCacheAction.java

@@ -14,13 +14,16 @@
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.Scope;
+import org.elasticsearch.rest.ServerlessScope;
 import org.elasticsearch.rest.action.RestToXContentListener;
 
 import java.io.IOException;
 import java.util.List;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
 
+@ServerlessScope(value = Scope.INTERNAL)
 public class RestClearIndicesCacheAction extends BaseRestHandler {
 
     @Override

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestFieldUsageStatsAction.java

@@ -16,12 +16,15 @@
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestHandler;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.Scope;
+import org.elasticsearch.rest.ServerlessScope;
 import org.elasticsearch.rest.action.RestCancellableNodeClient;
 import org.elasticsearch.rest.action.RestChunkedToXContentListener;
 
 import java.io.IOException;
 import java.util.List;
 
+@ServerlessScope(value = Scope.INTERNAL)
 public class RestFieldUsageStatsAction extends BaseRestHandler {
 
     @Override

server/src/main/java/org/elasticsearch/rest/action/search/RestExplainAction.java

@@ -15,6 +15,8 @@
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.Scope;
+import org.elasticsearch.rest.ServerlessScope;
 import org.elasticsearch.rest.action.RestActions;
 import org.elasticsearch.rest.action.RestStatusToXContentListener;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
@@ -28,6 +30,7 @@
 /**
  * Rest action for computing a score explanation for specific documents.
  */
+@ServerlessScope(value = Scope.PUBLIC)
 public class RestExplainAction extends BaseRestHandler {
     public static final String TYPES_DEPRECATION_MESSAGE = "[types removal] Specifying a type in explain requests is deprecated.";