[AINode] Optimize the statuscode for remove AINode (#17176)

Author: CRZbulabula

iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/manager/node/NodeManager.java

@@ -558,7 +558,7 @@ public synchronized DataSet registerAINode(TAINodeRegisterReq req) {
   public TSStatus removeAINode() {
     // check if the node exists
     if (nodeInfo.getRegisteredAINodes().isEmpty()) {
-      return new TSStatus(TSStatusCode.REMOVE_AI_NODE_ERROR.getStatusCode())
+      return new TSStatus(TSStatusCode.NO_REGISTERED_AI_NODE_ERROR.getStatusCode())
           .setMessage("Remove AINode failed because there is no AINode in the cluster.");
     }
 

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/executor/ClusterConfigTaskExecutor.java

@@ -3550,15 +3550,16 @@ public SettableFuture<ConfigTaskResult> removeAINode(
     LOGGER.info("Starting to remove AINode");
     try (ConfigNodeClient configNodeClient =
         CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
-      TShowClusterResp showClusterResp = configNodeClient.showCluster();
-      if (showClusterResp.getAiNodeListSize() < 1) {
-        LOGGER.error("Remove AINode failed because there is no AINode in the cluster.");
-        future.setException(
-            new IOException("Remove AINode failed because there is no AINode in the cluster."));
-        return future;
-      }
       TSStatus status = configNodeClient.removeAINode(new TAINodeRemoveReq());
-      if (status.getCode() != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
+      if (status.getCode() == TSStatusCode.NO_REGISTERED_AI_NODE_ERROR.getStatusCode()) {
+        LOGGER.warn("Remove AINode failed because there is no AINode in the cluster.");
+        future.set(
+            new ConfigTaskResult(
+                new TSStatus(TSStatusCode.NO_REGISTERED_AI_NODE_ERROR.getStatusCode())
+                    .setMessage(
+                        "Remove AINode failed because there is no AINode in the cluster.")));
+        return future;
+      } else if (status.getCode() != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
         future.setException(new IOException("Remove AINode failed: " + status.getMessage()));
         return future;
       } else {