delete BIGINT_DEFAULT

Author: kevinyu98

sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala

@@ -109,7 +109,6 @@ object DecimalType extends AbstractDataType {
   val MAX_SCALE = 38
   val SYSTEM_DEFAULT: DecimalType = DecimalType(MAX_PRECISION, 18)
   val USER_DEFAULT: DecimalType = DecimalType(10, 0)
-  val BIGINT_DEFAULT: DecimalType = DecimalType(MAX_PRECISION, 0)
 
   // The decimal types compatible with other numeric types
   private[sql] val ByteDecimal = DecimalType(3, 0)