KAFKA-8563: Remove redundant `NetworkSend.sizeDelimit()` method (#6967)

Reviewers: Ismael Juma <ismael@juma.me.uk>

clients/src/main/java/org/apache/kafka/common/network/NetworkSend.java

@@ -24,11 +24,7 @@ import java.nio.ByteBuffer;
 public class NetworkSend extends ByteBufferSend {
 
     public NetworkSend(String destination, ByteBuffer buffer) {
-        super(destination, sizeDelimit(buffer));
+        super(destination, sizeBuffer(buffer.remaining()), buffer);
-    }
-
-    private static ByteBuffer[] sizeDelimit(ByteBuffer buffer) {
-        return new ByteBuffer[] {sizeBuffer(buffer.remaining()), buffer};
     }
 
     private static ByteBuffer sizeBuffer(int size) {