[SPARK-16776][STREAMING] Replace deprecated API in KafkaTestUtils for 0.10.0.

## What changes were proposed in this pull request?

This PR replaces the old Kafka API to 0.10.0 ones in `KafkaTestUtils`.

The change include:

 - `Producer` to `KafkaProducer`
 - Change configurations to equalvant ones. (I referred [here](http://kafka.apache.org/documentation.html#producerconfigs) for 0.10.0 and [here](http://kafka.apache.org/082/documentation.html#producerconfigs
) for old, 0.8.2).

This PR will remove the build warning as below:

```scala
[WARNING] .../spark/external/kafka-0-10/src/main/scala/org/apache/spark/streaming/kafka010/KafkaTestUtils.scala:71: class Producer in package producer is deprecated: This class has been deprecated and will be removed in a future release. Please use org.apache.kafka.clients.producer.KafkaProducer instead.
[WARNING]   private var producer: Producer[String, String] = _
[WARNING]                         ^
[WARNING] .../spark/external/kafka-0-10/src/main/scala/org/apache/spark/streaming/kafka010/KafkaTestUtils.scala:181: class Producer in package producer is deprecated: This class has been deprecated and will be removed in a future release. Please use org.apache.kafka.clients.producer.KafkaProducer instead.
[WARNING]     producer = new Producer[String, String](new ProducerConfig(producerConfiguration))
[WARNING]                    ^
[WARNING] .../spark/streaming/kafka010/KafkaTestUtils.scala:181: class ProducerConfig in package producer is deprecated: This class has been deprecated and will be removed in a future release. Please use org.apache.kafka.clients.producer.ProducerConfig instead.
[WARNING]     producer = new Producer[String, String](new ProducerConfig(producerConfiguration))
[WARNING]                                                 ^
[WARNING] .../spark/external/kafka-0-10/src/main/scala/org/apache/spark/streaming/kafka010/KafkaTestUtils.scala:182: class KeyedMessage in package producer is deprecated: This class has been deprecated and will be removed in a future release. Please use org.apache.kafka.clients.producer.ProducerRecord instead.
[WARNING]     producer.send(messages.map { new KeyedMessage[String, String](topic, _ ) }: _*)
[WARNING]                                      ^
[WARNING] four warnings found
[WARNING] warning: [options] bootstrap class path not set in conjunction with -source 1.7
[WARNING] 1 warning
```

## How was this patch tested?

Existing tests that use `KafkaTestUtils` should cover this.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #14416 from HyukjinKwon/SPARK-16776.