[Tests] Remove not needed usings in the CoreAnimation tests. (#13251)

tests/monotouch-test/CoreAnimation/EmitterBehaviorTest.cs

@@ -9,7 +9,6 @@
 
 #if !__WATCHOS__
 
-using System;
 using Foundation;
 using CoreAnimation;
 using ObjCRuntime;

tests/monotouch-test/CoreAnimation/LayerTest.cs

@@ -11,7 +11,6 @@
 
 using System;
 using System.Diagnostics;
-using System.Drawing;
 using System.Linq;
 using System.Threading;
 using CoreGraphics;

tests/monotouch-test/CoreAnimation/MediaTimingFunctionTest.cs

@@ -10,11 +10,9 @@
 #if !__WATCHOS__
 
 using System;
-using System.Drawing;
 using CoreGraphics;
 using Foundation;
 using CoreAnimation;
-using ObjCRuntime;
 using NUnit.Framework;
 
 namespace MonoTouchFixtures.CoreMotion {

tests/monotouch-test/CoreAnimation/ShapeLayerTest.cs

@@ -9,7 +9,6 @@
 
 #if !__WATCHOS__
 
-using System;
 using Foundation;
 using CoreAnimation;
 using CoreGraphics;

tests/monotouch-test/CoreAnimation/TransactionTest.cs

@@ -9,7 +9,6 @@
 
 #if !__WATCHOS__
 
-using System;
 using CoreAnimation;
 using Foundation;
 using NUnit.Framework;