_scheduler: Fix dont display a failure for terminated jobs

This fixes a recent regression introduced in c2fc2a5e

buildstream/_scheduler/jobs/job.py

@@ -184,6 +184,16 @@ class Job():
 
         self._terminated = True
 
+    # get_terminated()
+    #
+    # Check if a job has been terminated.
+    #
+    # Returns:
+    #     (bool): True in the main process if Job.terminate() was called.
+    #
+    def get_terminated(self):
+        return self._terminated
+
     # terminate_wait()
     #
     # Wait for terminated jobs to complete

buildstream/_scheduler/queues/queue.py

@@ -305,7 +305,7 @@ class Queue():
             self._done_queue.append(element)
 
             # These lists are for bookkeeping purposes for the UI and logging.
-            if status == JobStatus.SKIPPED:
+            if status == JobStatus.SKIPPED or job.get_terminated():
                 self.skipped_elements.append(element)
             elif status == JobStatus.OK:
                 self.processed_elements.append(element)