[SPARK-26969][SQL] Using ODBC client not able to see the query data when column datatype is decimal

## What changes were proposed in this pull request?
While processing the Rowdata in the server side ColumnValue BigDecimal type value processed by server has to converted to the HiveDecmal data type for successful processing of query using Hive ODBC client.As per current logic  corresponding to the Decimal column datatype, the Spark server uses BigDecimal, and the ODBC client uses HiveDecimal. If the data type does not match, the client fail to parse

Since this handing was missing the query executed in Hive ODBC client wont return or provides result to the user even though the decimal type column value data present.

## How was this patch tested?

Manual test report and impact assessment is done using existing test-cases

Before fix
![decimal_odbc](https://user-images.githubusercontent.com/12999161/53440179-e74a7f00-3a29-11e9-93db-83f2ae37ef16.PNG)

After Fix
![hive_odbc](https://user-images.githubusercontent.com/12999161/53679519-70e0a200-3cf3-11e9-9437-9c27d2e5056d.PNG)

Closes #23899 from sujith71955/master_decimalissue.

Authored-by: s71955 <sujithchacko.2010@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

Author: sujith71955

sql/hive-thriftserver/src/test/scala/org/apache/spark/sql/hive/thriftserver/SparkThriftServerProtocolVersionsSuite.scala

@@ -186,8 +186,7 @@ class SparkThriftServerProtocolVersionsSuite extends HiveThriftJdbcTest {
       }
     }
 
-    // TODO: enable this test case after SPARK-28463 and SPARK-26969
-    ignore(s"$version get decimal type") {
+    test(s"$version get decimal type") {
       testExecuteStatementWithProtocolVersion(version,
         "SELECT cast(1 as decimal(18, 2)) as c") { rs =>
         assert(rs.next())

sql/hive-thriftserver/v1.2.1/src/main/java/org/apache/hive/service/cli/ColumnValue.java

@@ -23,7 +23,6 @@
 import java.sql.Timestamp;
 
 import org.apache.hadoop.hive.common.type.HiveChar;
-import org.apache.hadoop.hive.common.type.HiveDecimal;
 import org.apache.hadoop.hive.common.type.HiveIntervalDayTime;
 import org.apache.hadoop.hive.common.type.HiveIntervalYearMonth;
 import org.apache.hadoop.hive.common.type.HiveVarchar;
@@ -140,14 +139,6 @@ private static TColumnValue timestampValue(Timestamp value) {
     return TColumnValue.stringVal(tStringValue);
   }
 
-  private static TColumnValue stringValue(HiveDecimal value) {
-    TStringValue tStrValue = new TStringValue();
-    if (value != null) {
-      tStrValue.setValue(value.toString());
-    }
-    return TColumnValue.stringVal(tStrValue);
-  }
-
   private static TColumnValue stringValue(HiveIntervalYearMonth value) {
     TStringValue tStrValue = new TStringValue();
     if (value != null) {
@@ -195,7 +186,7 @@ public static TColumnValue toTColumnValue(Type type, Object value) {
     case INTERVAL_DAY_TIME_TYPE:
       return stringValue((HiveIntervalDayTime) value);
     case DECIMAL_TYPE:
-      return stringValue(((HiveDecimal)value));
+      return stringValue(((BigDecimal)value).toPlainString());
     case BINARY_TYPE:
       String strVal = value == null ? null : UTF8String.fromBytes((byte[])value).toString();
       return stringValue(strVal);

sql/hive-thriftserver/v2.3.5/src/main/java/org/apache/hive/service/cli/ColumnValue.java

@@ -23,7 +23,6 @@
 import java.sql.Timestamp;
 
 import org.apache.hadoop.hive.common.type.HiveChar;
-import org.apache.hadoop.hive.common.type.HiveDecimal;
 import org.apache.hadoop.hive.common.type.HiveIntervalDayTime;
 import org.apache.hadoop.hive.common.type.HiveIntervalYearMonth;
 import org.apache.hadoop.hive.common.type.HiveVarchar;
@@ -141,15 +140,6 @@ private static TColumnValue timestampValue(Timestamp value) {
     return TColumnValue.stringVal(tStringValue);
   }
 
-  private static TColumnValue stringValue(HiveDecimal value, TypeDescriptor typeDescriptor) {
-    TStringValue tStrValue = new TStringValue();
-    if (value != null) {
-      int scale = typeDescriptor.getDecimalDigits();
-      tStrValue.setValue(value.toFormatString(scale));
-    }
-    return TColumnValue.stringVal(tStrValue);
-  }
-
   private static TColumnValue stringValue(HiveIntervalYearMonth value) {
     TStringValue tStrValue = new TStringValue();
     if (value != null) {
@@ -199,7 +189,7 @@ public static TColumnValue toTColumnValue(TypeDescriptor typeDescriptor, Object
     case INTERVAL_DAY_TIME_TYPE:
       return stringValue((HiveIntervalDayTime) value);
     case DECIMAL_TYPE:
-      return stringValue((HiveDecimal)value, typeDescriptor);
+      return stringValue(((BigDecimal)value).toPlainString());
     case BINARY_TYPE:
       String strVal = value == null ? null : UTF8String.fromBytes((byte[])value).toString();
       return stringValue(strVal);