Report item stats when removing a change

If a change is removed outside of the main process method (eg
it is superceded), stats were not reported.  Report them in that
case.

Change-Id: I9e753599dc3ecdf0d4bffc04f4515c04d882c8be

zuul/scheduler.py

@@ -845,6 +845,7 @@ class BasePipelineManager(object):
                                "because it is being removed." % item.change)
                 self.cancelJobs(item)
                 self.dequeueItem(item, keep_severed_heads=False)
+                self.reportStats(item)
 
     def prepareRef(self, item):
         # Returns False on success.