[COOK-3410] Redundant ntpdate/disable recipes

https://tickets.opscode.com/browse/COOK-3410

* Ensure idempotence for ntp::undo by removing only if conflicting state exists in run_list
* Remove redundant, and confusingly named disable recipe, ntp::undo * serves this purpose.
* Remove ntpdate recipe.
  - This is not a service, it is _NOT_ a thing to be managed.  This
    recipe only affects the redundant ntpdate-debian command.  There is
    little purpose in disabling a command which is not called from the
    host recipe.