Disable stats recorder for built-in PulsarClient (#12217)

### Motivation

In `PulsarService`, there's a built-in client used in many places, like topic compaction, system topics read/write. It could also be used in protocol handlers. Different with the manually created Pulsar client, it can read the configured authentication params and TLS related configs for broker-to-broker communication.

However, it doesn't change the default `statsIntervalSeconds` config, which means each time a producer/consumer/reader is created, a stats recorder (`ProducerStatsRecorderImpl` or `ConsumerStatsRecorderImpl`) will be created, in which there's a Netty `TimerTask` that prints stats periodically (the default interval is 1 minute). If there're many producers/consumers/readers created by this built-in client, the unnecessary CPU usage will be high.

### Modifications

Configure the `statsIntervalSeconds` with zero value to disable stats recorder.

pulsar-broker/src/main/java/org/apache/pulsar/broker/PulsarService.java

@@ -1327,6 +1327,8 @@ public synchronized PulsarClient getClient() throws PulsarServerException {
                             this.getConfiguration().getBrokerClientAuthenticationPlugin(),
                             this.getConfiguration().getBrokerClientAuthenticationParameters()));
                 }
+
+                conf.setStatsIntervalSeconds(0);
                 this.client = new PulsarClientImpl(conf, ioEventLoopGroup);
             } catch (Exception e) {
                 throw new PulsarServerException(e);