JS: delete the TrackedNodes.qll, it had no public interface left

Author: erik-krogh

javascript/ql/lib/semmle/javascript/dataflow/DataFlow.qll

@@ -1715,7 +1715,6 @@ module DataFlow {
   import Sources
   import TypeInference
   import Configuration
-  import TrackedNodes
   import TypeTracking
   import internal.FunctionWrapperSteps