cleanup using namespaces

Author: IJEMIN

Assets/Benchmark/FrameData.cs

@@ -1,4 +1,3 @@
-using System;
 using System.Collections.Generic;
 using UnityEngine;
 

Assets/Benchmark/PerformanceTestStage.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using UnityEngine;

Assets/Benchmark/PerformanceTestUtilities.cs

@@ -1,6 +1,3 @@
-using System.Collections;
-using System.Collections.Generic;
-using UnityEngine;
 using UnityEngine.UIElements;
 
 namespace Benchmarking

Assets/Benchmark/StatsGraphVE.cs

@@ -1,10 +1,7 @@
 using System;
-using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
 using UnityEngine;
 using UnityEngine.UIElements;
-using Unity.Burst;
 
 namespace Benchmarking
 {