Revert "NewcomerTaskStore: update the task queue before finishing loading"

This reverts commit 86435e2ab5.

Reason for revert: caused T360469, which Kirsten considers to be
more problematic

Bug: T360469
Bug: T359992
Change-Id: I9c8da6321e1bdbb9b33b03addb183c06daf8c4ef

modules/ext.growthExperiments.DataStore/NewcomerTasksStore.js

@@ -353,8 +353,8 @@ NewcomerTasksStore.prototype.fetchTasks = function ( context, config ) {
 			this.taskCount = updatedTaskQueue.length;
 		}
 
-		this.setTaskQueue( updatedTaskQueue );
 		this.setTaskQueueLoading( false );
+		this.setTaskQueue( updatedTaskQueue );
 
 		if ( this.taskQueue.length ) {
 			this.maybeUpdateQualityGateConfig( this.taskQueue[ 0 ] );