provider/aws: Update aws_appautoscaling_target_test (#9736)

The update of the test was causing a test failure - it was setting
desired_count to 1 when miz_size was set to 2 - this was causing a
perpetual diff in the test

builtin/providers/aws/resource_aws_appautoscaling_target_test.go

@@ -284,7 +284,7 @@ resource "aws_ecs_service" "service" {
 	name = "foobar"
 	cluster = "${aws_ecs_cluster.foo.id}"
 	task_definition = "${aws_ecs_task_definition.task.arn}"
-	desired_count = 1
+	desired_count = 2
 
 	deployment_maximum_percent = 200
 	deployment_minimum_healthy_percent = 50