[pulsar-perf] Make it possible to disable poolMessages (apache#12090)

- JCommander requires passing arity = 1 to boolean parameters that
  have a default value of true.

pulsar-testclient/src/main/java/org/apache/pulsar/testclient/PerformanceConsumer.java

@@ -176,11 +176,11 @@ static class Arguments {
         @Parameter(names = {"-ioThreads", "--num-io-threads"}, description = "Set the number of threads to be " +
                 "used for handling connections to brokers, default is 1 thread")
         public int ioThreads = 1;
-    
+
         @Parameter(names = {"--batch-index-ack" }, description = "Enable or disable the batch index acknowledgment")
         public boolean batchIndexAck = false;
 
-        @Parameter(names = { "-pm", "--pool-messages" }, description = "Use the pooled message")
+        @Parameter(names = { "-pm", "--pool-messages" }, description = "Use the pooled message", arity = 1)
         private boolean poolMessages = true;
 
         @Parameter(names = {"-bw", "--busy-wait"}, description = "Enable Busy-Wait on the Pulsar client")