[SPARK-32568][BUILD][SS] Upgrade Kafka to 2.6.0

### What changes were proposed in this pull request?

This PR aims to update Kafka client library to 2.6.0 for Apache Spark 3.1.0.

### Why are the changes needed?

This will bring client-side bug fixes like KAFKA-10134 and KAFKA-10223.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the existing tests.

Closes #29386 from dongjoon-hyun/SPARK-32568.

Authored-by: Dongjoon Hyun <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

external/kafka-0-10-sql/src/test/scala/org/apache/spark/sql/kafka010/KafkaTestUtils.scala

@@ -395,7 +395,7 @@ class KafkaTestUtils(
   }
 
   def getAllTopicsAndPartitionSize(): Seq[(String, Int)] = {
-    zkClient.getPartitionsForTopics(zkClient.getAllTopicsInCluster).mapValues(_.size).toSeq
+    zkClient.getPartitionsForTopics(zkClient.getAllTopicsInCluster()).mapValues(_.size).toSeq
   }
 
   /** Create a Kafka topic and wait until it is propagated to the whole cluster */
@@ -587,7 +587,7 @@ class KafkaTestUtils(
     }), s"checkpoint for topic $topic still exists")
     // ensure the topic is gone
     assert(
-      !zkClient.getAllTopicsInCluster.contains(topic),
+      !zkClient.getAllTopicsInCluster().contains(topic),
       s"topic $topic still exists on zookeeper")
   }
 

pom.xml

@@ -133,7 +133,7 @@
     <!-- Version used for internal directory structure -->
     <hive.version.short>2.3</hive.version.short>
     <!-- note that this should be compatible with Kafka brokers version 0.10 and up -->
-    <kafka.version>2.5.0</kafka.version>
+    <kafka.version>2.6.0</kafka.version>
     <derby.version>10.12.1.1</derby.version>
     <parquet.version>1.10.1</parquet.version>
     <orc.version>1.5.10</orc.version>