Use Netty's pooled memory allocator

Instead of the adaptative one, which is the default in 4.2.
The pooled allocator was the default in 4.1.

Author: acogoluegnes

src/main/java/com/rabbitmq/stream/perf/StreamPerfTest.java

@@ -803,7 +803,7 @@ public Integer call() throws Exception {
     overridePropertiesWithEnvironmentVariables();
     Codec codec = createCodec(this.codecClass);
 
-    ByteBufAllocator byteBufAllocator = ByteBufAllocator.DEFAULT;
+    ByteBufAllocator byteBufAllocator = Utils.byteBufAllocator();
 
     CompositeMeterRegistry meterRegistry = new CompositeMeterRegistry();
     meterRegistry.config().commonTags(this.metricsTags);

src/main/java/com/rabbitmq/stream/perf/Utils.java

@@ -26,6 +26,8 @@
 import io.micrometer.core.instrument.dropwizard.DropwizardConfig;
 import io.micrometer.core.instrument.dropwizard.DropwizardMeterRegistry;
 import io.micrometer.core.instrument.util.HierarchicalNameMapper;
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.buffer.PooledByteBufAllocator;
 import java.io.PrintWriter;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
@@ -186,6 +188,10 @@ static String formatByte(double bytes) {
     return String.format("%.1f %cB", bytes / 1000.0, ci.current());
   }
 
+  static ByteBufAllocator byteBufAllocator() {
+    return PooledByteBufAllocator.DEFAULT;
+  }
+
   static long physicalMemory() {
     try {
       return TOTAL_MEMORY_SIZE_SUPPLIER.getAsLong();