[HOTFIX] Add back intended change from SPARK-15392

This was accidentally reverted in f8d0177.

Author: Andrew Or

sql/core/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -595,8 +595,7 @@ private[sql] class SQLConf extends Serializable with CatalystConf with Logging {
 
   def enableRadixSort: Boolean = getConf(RADIX_SORT_ENABLED)
 
-  def defaultSizeInBytes: Long =
-    getConf(DEFAULT_SIZE_IN_BYTES, autoBroadcastJoinThreshold + 1L)
+  def defaultSizeInBytes: Long = getConf(DEFAULT_SIZE_IN_BYTES, Long.MaxValue)
 
   def isParquetBinaryAsString: Boolean = getConf(PARQUET_BINARY_AS_STRING)