[KYUUBI #1105][FOLLOWUP] Minor improve ZorderBytesUtils.defaultValue

<!--
Thanks for sending a pull request!

Here are some tips for you:
  1. If this is your first time, please read our contributor guidelines: https://kyuubi.readthedocs.io/en/latest/community/contributions.html
  2. If the PR is related to an issue in https://github.com/apache/incubator-kyuubi/issues, add '[KYUUBI #XXXX]' in your PR title, e.g., '[KYUUBI #XXXX] Your PR title ...'.
  3. If the PR is unfinished, add '[WIP]' in your PR title, e.g., '[WIP][KYUUBI #XXXX] Your PR title ...'.
-->

### _Why are the changes needed?_
<!--
Please clarify why the changes are needed. For instance,
  1. If you add a feature, you can talk about the use case of it.
  2. If you fix a bug, you can clarify why it is a bug.
-->

fix [comment](https://github.com/apache/incubator-kyuubi/pull/1109#discussion_r711007709)

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [ ] Add screenshots for manual tests if appropriate

- [x] [Run test](https://kyuubi.readthedocs.io/en/latest/develop_tools/testing.html#running-tests) locally before make a pull request

Closes #1126 from cfmcgrady/zorder.

Closes #1105

48e4d73a [Fu Chen] review
a58c5e52 [Fu Chen] minor improve ZorderBytesUtils.defaultValue

Authored-by: Fu Chen <cfmcgrady@gmail.com>
Signed-off-by: Cheng Pan <chengpan@apache.org>

dev/kyuubi-extension-spark-3-1/src/main/scala/org/apache/kyuubi/sql/zorder/Zorder.scala

@@ -46,7 +46,6 @@ case class Zorder(children: Seq[Expression]) extends Expression {
   private lazy val defaultNullValues: Array[Array[Byte]] =
     children.map(_.dataType)
       .map(ZorderBytesUtils.defaultValue)
-      .map(ZorderBytesUtils.toByte)
       .toArray
 
   override def eval(input: InternalRow): Any = {

dev/kyuubi-extension-spark-3-1/src/main/scala/org/apache/kyuubi/sql/zorder/ZorderBytesUtils.scala

@@ -171,30 +171,27 @@ object ZorderBytesUtils {
     result
   }
 
-  def defaultValue(dataType: DataType): Any = dataType match {
-    case BooleanType =>
-      false
-    case ByteType =>
-      Byte.MaxValue
-    case ShortType =>
-      Short.MaxValue
-    case IntegerType =>
-      Int.MaxValue
-    case LongType =>
-      Long.MaxValue
-    case FloatType =>
-      Float.MaxValue
-    case DoubleType =>
-      Double.MaxValue
-    case StringType =>
-      UTF8String.fromBytes(new Array[Byte](0))
-    case TimestampType =>
-      Long.MaxValue
-    case DateType =>
-      Int.MaxValue
-    case _: DecimalType =>
-      Long.MaxValue
-    case other: Any =>
-      throw new KyuubiSQLExtensionException(s"Unsupported z-order type: ${other.catalogString}")
+  def defaultValue(dataType: DataType): Array[Byte] = {
+    val v = dataType match {
+      case BooleanType =>
+        false
+      case ByteType =>
+        Byte.MaxValue
+      case ShortType =>
+        Short.MaxValue
+      case IntegerType | DateType =>
+        Int.MaxValue
+      case LongType | TimestampType | _: DecimalType =>
+        Long.MaxValue
+      case FloatType =>
+        Float.MaxValue
+      case DoubleType =>
+        Double.MaxValue
+      case StringType =>
+        UTF8String.fromBytes(new Array[Byte](0))
+      case other: Any =>
+        throw new KyuubiSQLExtensionException(s"Unsupported z-order type: ${other.catalogString}")
+    }
+    toByte(v)
   }
 }