@HiveDecimalVersionV2
  public int bigIntegerBytesScaled(
      int serializeScale,
      long[] scratchLongs, byte[] buffer) {
    return
        fastBigIntegerBytesScaled(
            serializeScale,
            scratchLongs, buffer);
  }
Convert decimal to BigInteger binary bytes with a serialize scale, similar to the formatScale
for toFormatString.  It adds trailing zeroes the (emulated) BigInteger toByteArray result
when a serializeScale is greater than current scale.  Or, rounds if scale is less than
current scale.
<p>
Used by Avro and Parquet serialization.
<p>
This emulates the OldHiveDecimal setScale AND THEN OldHiveDecimal getInternalStorage() behavior.
storage-api/src/java/org/apache/hadoop/hive/common/type/HiveDecimal.java