fix the race of delete subscription and delete topic (#12240)

(cherry picked from commit 9137e6b)

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

@@ -1020,6 +1020,11 @@ public void deleteCursorFailed(ManagedLedgerException exception, Object ctx) {
                     log.debug("[{}][{}] Error deleting cursor for subscription",
                             topic, subscriptionName, exception);
                 }
+                if (exception instanceof ManagedLedgerException.ManagedLedgerNotFoundException) {
+                    unsubscribeFuture.complete(null);
+                    lastActive = System.nanoTime();
+                    return;
+                }
                 unsubscribeFuture.completeExceptionally(new PersistenceException(exception));
             }
         }, null);