Fix a failure in System.Reflection.DispatchProxy.Tests on ILC

- unnecessary metadata dependency in Assert error string.

Author: Atsushi Kanamori

src/System.Reflection.DispatchProxy/tests/DispatchProxyTests.cs

@@ -70,7 +70,7 @@ public static void Create_Proxy_Instances_Of_Same_Proxy_And_Base_Type_Are_Unique
             Assert.NotNull(proxy1);
             Assert.NotNull(proxy2);
             Assert.False(object.ReferenceEquals(proxy1, proxy2),
-                        String.Format("First and second instance of proxy type {0} were the same instance", proxy1.GetType().Name));
+                        String.Format("First and second instance of proxy type {0} were the same instance", proxy1.GetType().ToString()));
         }