Remove synchronization for updateFinalTaskInfo()

During lock profiling we observed that there is some contention
when calling SqlStageExecution.updateFinalTaskInfo().
runningTasks used inside this method is a thread safe hashset.
Also the stateMachine.setAllTasksFinal() is thread safe, as it
acquires locks before execution. So its safe to remvoe the
"synchronized" for updateFinalTaskInfo().

Author: NikhilCollooru

presto-main/src/main/java/com/facebook/presto/execution/SqlStageExecution.java

@@ -718,13 +718,13 @@ private boolean isRecoverable(List<ExecutionFailureInfo> failures)
                 failedTasks.size() < allTasks.size() * maxFailedTaskPercentage;
     }
 
-    private synchronized void updateFinalTaskInfo(TaskInfo finalTaskInfo)
+    private void updateFinalTaskInfo(TaskInfo finalTaskInfo)
     {
         runningTasks.remove(finalTaskInfo.getTaskId());
         checkAllTaskFinal();
     }
 
-    private synchronized void checkAllTaskFinal()
+    private void checkAllTaskFinal()
     {
         if (stateMachine.getState().isDone() && runningTasks.isEmpty()) {
             if (getFragment().getStageExecutionDescriptor().isStageGroupedExecution()) {