feat(broker): fix ExtensibleLoadManagerImplTest.testDisableBroker

Author: Denovo1998

pulsar-broker/src/main/java/org/apache/pulsar/broker/loadbalance/extensions/channel/ServiceUnitStateChannelImpl.java

@@ -460,7 +460,10 @@ private CompletableFuture<Optional<String>> getActiveOwnerAsync(
             String serviceUnit,
             ServiceUnitState state,
             Optional<String> owner) {
-
+        // If the channel is disabled or closed, this broker cannot be an active owner.
+        if (channelState == Disabled || channelState == Closed) {
+            return CompletableFuture.completedFuture(Optional.empty());
+        }
         // If this broker's registry does not exist(possibly suffering from connecting to the metadata store),
         // we return the owner without its activeness check.
         // This broker tries to serve lookups on a best efforts basis when metadata store connection is unstable.