Condition 'policies != null' is always 'true' ,no need to judge. (#13577)

Co-authored-by: lightzhao <zhaoliang01@58.com>
diff --git a/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/AbstractTopic.java b/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/AbstractTopic.java
index d452625..56245a6 100644
--- a/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/AbstractTopic.java
+++ b/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/AbstractTopic.java
@@ -899,7 +899,7 @@
         }
 
         // attach the resource-group level rate limiters, if set
-        String rgName = policies != null && policies.resource_group_name != null
+        String rgName = policies.resource_group_name != null
           ? policies.resource_group_name
           : null;
         if (rgName != null) {