Remove unused import and small cleanup.

Author: ueshin

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/CatalystConf.scala

@@ -67,5 +67,5 @@ case class SimpleCatalystConf(
     runSQLonFile: Boolean = true,
     crossJoinEnabled: Boolean = false,
     warehousePath: String = "/user/hive/warehouse",
-    sessionLocalTimeZone: String = TimeZone.getDefault.getID)
+    sessionLocalTimeZone: String = TimeZone.getDefault().getID)
   extends CatalystConf

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala

@@ -17,8 +17,6 @@
 
 package org.apache.spark.sql.catalyst.analysis
 
-import java.util.TimeZone
-
 import scala.annotation.tailrec
 import scala.collection.mutable.ArrayBuffer
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala

@@ -18,7 +18,6 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import java.math.{BigDecimal => JavaBigDecimal}
-import java.util.TimeZone
 
 import org.apache.spark.SparkException
 import org.apache.spark.sql.catalyst.InternalRow

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala

@@ -18,7 +18,6 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import java.sql.{Date, Timestamp}
-import java.text.SimpleDateFormat
 import java.util.{Calendar, Locale, TimeZone}
 
 import org.apache.spark.SparkFunSuite