[SPARK-21953] Show both memory and disk bytes spilled if either is present

As written now, there must be both memory and disk bytes spilled to show either of them. If there is only one of those types of spill recorded, it will be hidden.

Author: Andrew Ash <andrew@andrewash.com>

Closes #19164 from ash211/patch-3.

(cherry picked from commit 6308c65f)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala

@@ -104,7 +104,7 @@ private[spark] object UIData {
     def hasOutput: Boolean = outputBytes > 0
     def hasShuffleRead: Boolean = shuffleReadTotalBytes > 0
     def hasShuffleWrite: Boolean = shuffleWriteBytes > 0
-    def hasBytesSpilled: Boolean = memoryBytesSpilled > 0 && diskBytesSpilled > 0
+    def hasBytesSpilled: Boolean = memoryBytesSpilled > 0 || diskBytesSpilled > 0
   }
 
   /**