Remove duplicate assignment in Task::toJson method (facebookincubator…

…#10704)

Summary:
The Task::toJson method currently contains a duplicate assignment of the numDriversUngrouped_ attribute, which is unnecessary and redundant.
This commit removes the superfluous line to clean up the code and prevent any potential confusion.

Pull Request resolved: facebookincubator#10704

Reviewed By: Yuhta

Differential Revision: D61218912

Pulled By: xiaoxmeng

fbshipit-source-id: 4e8ddb264734bfcf7927d4473cf4f04883dff8a9

velox/exec/Task.cpp

@@ -2338,7 +2338,6 @@ folly::dynamic Task::toJson() const {
   obj["groupedPartitionedOutput"] = groupedPartitionedOutput_;
   obj["concurrentSplitGroups"] = concurrentSplitGroups_;
   obj["numRunningSplitGroups"] = numRunningSplitGroups_;
-  obj["numDriversUngrouped"] = numDriversUngrouped_;
   obj["partitionedOutputConsumed"] = partitionedOutputConsumed_;
   obj["noMoreOutputBuffers"] = noMoreOutputBuffers_;
   obj["onThreadSince"] = std::to_string(onThreadSince_);