[SPARK-16358][SQL] Remove InsertIntoHiveTable From Logical Plan

#### What changes were proposed in this pull request?
LogicalPlan `InsertIntoHiveTable` is useless. Thus, we can remove it from the code base.

#### How was this patch tested?
The existing test cases

Author: gatorsmile <gatorsmile@gmail.com>

Closes #14037 from gatorsmile/InsertIntoHiveTable.

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala

@@ -372,12 +372,6 @@ private[hive] class HiveMetastoreCatalog(sparkSession: SparkSession) extends Log
           if !r.hiveQlTable.isPartitioned && shouldConvertMetastoreParquet(r) =>
           InsertIntoTable(convertToParquetRelation(r), partition, child, overwrite, ifNotExists)
 
-        // Write path
-        case InsertIntoHiveTable(r: MetastoreRelation, partition, child, overwrite, ifNotExists)
-          // Inserting into partitioned table is not supported in Parquet data source (yet).
-          if !r.hiveQlTable.isPartitioned && shouldConvertMetastoreParquet(r) =>
-          InsertIntoTable(convertToParquetRelation(r), partition, child, overwrite, ifNotExists)
-
         // Read path
         case relation: MetastoreRelation if shouldConvertMetastoreParquet(relation) =>
           val parquetRelation = convertToParquetRelation(relation)
@@ -416,12 +410,6 @@ private[hive] class HiveMetastoreCatalog(sparkSession: SparkSession) extends Log
           if !r.hiveQlTable.isPartitioned && shouldConvertMetastoreOrc(r) =>
           InsertIntoTable(convertToOrcRelation(r), partition, child, overwrite, ifNotExists)
 
-        // Write path
-        case InsertIntoHiveTable(r: MetastoreRelation, partition, child, overwrite, ifNotExists)
-          // Inserting into partitioned table is not supported in Orc data source (yet).
-          if !r.hiveQlTable.isPartitioned && shouldConvertMetastoreOrc(r) =>
-          InsertIntoTable(convertToOrcRelation(r), partition, child, overwrite, ifNotExists)
-
         // Read path
         case relation: MetastoreRelation if shouldConvertMetastoreOrc(relation) =>
           val orcRelation = convertToOrcRelation(relation)
@@ -489,30 +477,3 @@ private[hive] object MetaStorePartitionedTableFileCatalog {
     }
   }
 }
-
-/**
- * A logical plan representing insertion into Hive table.
- * This plan ignores nullability of ArrayType, MapType, StructType unlike InsertIntoTable
- * because Hive table doesn't have nullability for ARRAY, MAP, STRUCT types.
- */
-private[hive] case class InsertIntoHiveTable(
-    table: MetastoreRelation,
-    partition: Map[String, Option[String]],
-    child: LogicalPlan,
-    overwrite: Boolean,
-    ifNotExists: Boolean)
-  extends LogicalPlan with Command {
-
-  override def children: Seq[LogicalPlan] = child :: Nil
-  override def output: Seq[Attribute] = Seq.empty
-
-  val numDynamicPartitions = partition.values.count(_.isEmpty)
-
-  // This is the expected schema of the table prepared to be inserted into,
-  // including dynamic partition columns.
-  val tableOutput = table.attributes ++ table.partitionKeys.takeRight(numDynamicPartitions)
-
-  override lazy val resolved: Boolean = childrenResolved && child.output.zip(tableOutput).forall {
-    case (childAttr, tableAttr) => childAttr.dataType.sameType(tableAttr.dataType)
-  }
-}

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveStrategies.scala

@@ -44,12 +44,7 @@ private[hive] trait HiveStrategies {
     def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
       case logical.InsertIntoTable(
           table: MetastoreRelation, partition, child, overwrite, ifNotExists) =>
-        execution.InsertIntoHiveTable(
-          table, partition, planLater(child), overwrite, ifNotExists) :: Nil
-      case hive.InsertIntoHiveTable(
-          table: MetastoreRelation, partition, child, overwrite, ifNotExists) =>
-        execution.InsertIntoHiveTable(
-          table, partition, planLater(child), overwrite, ifNotExists) :: Nil
+        InsertIntoHiveTable(table, partition, planLater(child), overwrite, ifNotExists) :: Nil
       case _ => Nil
     }
   }

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveComparisonTest.scala

@@ -31,7 +31,6 @@ import org.apache.spark.sql.catalyst.planning.PhysicalOperation
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.catalyst.util._
 import org.apache.spark.sql.execution.command._
-import org.apache.spark.sql.hive.{InsertIntoHiveTable => LogicalInsertIntoHiveTable}
 import org.apache.spark.sql.hive.test.{TestHive, TestHiveQueryExecution}
 
 /**
@@ -349,7 +348,6 @@ abstract class HiveComparisonTest
               val containsCommands = originalQuery.analyzed.collectFirst {
                 case _: Command => ()
                 case _: InsertIntoTable => ()
-                case _: LogicalInsertIntoHiveTable => ()
               }.nonEmpty
 
               if (containsCommands) {