tests: cgroup: re-enable the test for moving the task

Signed-off-by: Levente Kurusa <lkurusa@acm.org>

tests/cgroup.rs

@@ -23,9 +23,7 @@ fn test_tasks_iterator() {
         tasks = cg.tasks().into_iter();
 
         // Verify that it was indeed removed.
-        //assert_eq!(tasks.next(), None);
-        // ^ This is disabled, because it requires root privileges and there's no way around it
-        // right now.
+        assert_eq!(tasks.next(), None);
     }
     cg.delete();
 }