refactor: remove MapSort from shared code

MapSort only exists in Spark 4.0+, not in 3.4/3.5

Author: Shekharrajak

spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala

@@ -131,8 +131,7 @@ object QueryPlanSerde extends Logging with CometExprShim {
     classOf[MapValues] -> CometMapValues,
     classOf[MapFromArrays] -> CometMapFromArrays,
     classOf[MapContainsKey] -> CometMapContainsKey,
-    classOf[MapFromEntries] -> CometMapFromEntries,
-    classOf[MapSort] -> CometMapSort)
+    classOf[MapFromEntries] -> CometMapFromEntries)
 
   private val structExpressions: Map[Class[_ <: Expression], CometExpressionSerde[_]] = Map(
     classOf[CreateNamedStruct] -> CometCreateNamedStruct,

spark/src/main/scala/org/apache/comet/serde/maps.scala

@@ -20,7 +20,6 @@
 package org.apache.comet.serde
 
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.expressions.objects.RowOrdering
 import org.apache.spark.sql.types._
 
 import org.apache.comet.CometSparkSessionExtensions.withInfo
@@ -158,21 +157,3 @@ object CometMapFromEntries extends CometScalarFunction[MapFromEntries]("map_from
     Compatible(None)
   }
 }
-
-object CometMapSort extends CometExpressionSerde[MapSort] {
-
-  override def convert(
-      expr: MapSort,
-      inputs: Seq[Attribute],
-      binding: Boolean): Option[ExprOuterClass.Expr] = {
-    val keyType = expr.base.dataType.asInstanceOf[MapType].keyType
-    if (!RowOrdering.isOrderable(keyType)) {
-      withInfo(expr, s"map_sort requires orderable key type, got: $keyType")
-      return None
-    }
-
-    val childExpr = exprToProtoInternal(expr.base, inputs, binding)
-    val mapSortScalarExpr = scalarFunctionExprToProto("map_sort", childExpr)
-    optExprWithInfo(mapSortScalarExpr, expr, expr.children: _*)
-  }
-}