[fix] [broker] delete topic failed if disabled system topic (apache#19735)

Motivation: After PR apache#18823, The cmd delete topic will fail if disabled the feature system topic.
Modifications: do not delete the system policy if disabled the feature system topic

Author: poorbarcode

pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java

@@ -1246,7 +1246,8 @@ private CompletableFuture<Void> delete(boolean failIfHasSubscriptions,
 
                         deleteTopicAuthenticationFuture.thenCompose(ignore -> deleteSchema())
                                 .thenCompose(ignore -> {
-                                    if (!SystemTopicNames.isTopicPoliciesSystemTopic(topic)) {
+                                    if (!SystemTopicNames.isTopicPoliciesSystemTopic(topic)
+                                            && brokerService.getPulsar().getConfiguration().isSystemTopicEnabled()) {
                                         return deleteTopicPolicies();
                                     } else {
                                         return CompletableFuture.completedFuture(null);

pulsar-broker/src/test/java/org/apache/pulsar/client/impl/DisabledSystemTopicTest.java

@@ -0,0 +1,61 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.pulsar.client.impl;
+
+import java.util.UUID;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.pulsar.client.api.ProducerConsumerBase;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+@Slf4j
+@Test(groups = "broker")
+public class DisabledSystemTopicTest extends ProducerConsumerBase {
+
+    @Override
+    @BeforeMethod
+    public void setup() throws Exception {
+        super.internalSetup();
+        super.producerBaseSetup();
+    }
+
+    @Override
+    @AfterMethod(alwaysRun = true)
+    public void cleanup() throws Exception {
+        super.internalCleanup();
+    }
+
+    protected void doInitConf() throws Exception {
+        super.doInitConf();
+        conf.setTransactionCoordinatorEnabled(false);
+        conf.setSystemTopicEnabled(false);
+    }
+
+    @Test
+    public void testDeleteTopic() throws Exception {
+        String topicName = "persistent://my-property/my-ns/tp_" + UUID.randomUUID().toString();
+
+        admin.topics().createNonPartitionedTopic(topicName);
+        admin.topics().delete(topicName, false);
+
+        admin.topics().createPartitionedTopic(topicName, 3);
+        admin.topics().deletePartitionedTopic(topicName);
+    }
+}