MINOR: Fixed compiler warnings in LogManagerTest (#6897)

Reviewers: Jason Gustafson <jason@confluent.io>, Guozhang Wang <wangguoz@gmail.com>

core/src/test/scala/unit/kafka/log/LogManagerTest.scala

@@ -382,8 +382,8 @@ class LogManagerTest {
 
   @Test
   def testCreateAndDeleteOverlyLongTopic(): Unit = {
-    val invalidTopicName = String.join("", Collections.nCopies(253, "x"));
-    val log = logManager.getOrCreateLog(new TopicPartition(invalidTopicName, 0), logConfig)
+    val invalidTopicName = String.join("", Collections.nCopies(253, "x"))
+    logManager.getOrCreateLog(new TopicPartition(invalidTopicName, 0), logConfig)
     logManager.asyncDelete(new TopicPartition(invalidTopicName, 0))
   }