[MSC-131] always remove controller from all stability monitors if controller is transitioning from REMOVING to REMOVED

 * removed StabilityStatistics.getRemovedCount() because this statistics becomes invalid when this fix is applied
 * exposed ServiceContainer.isShutdown() method to be used instead of StabilityStatistics.getRemovedCount() in AS BootstrapListener
   in order to be able to detect ServiceContainer is going down.