[Notifications] When application responds to cancel request, stop kill timer

This ensures that an error message the app might have sent in response to the
cancel request is still shown.

Also, while at it deduplicate code by calling into `terminate` from the
service watcher.

libnotificationmanager/job_p.cpp

@@ -265,6 +265,10 @@ void JobPrivate::finish()
         return;
     }
 
+    if (m_killTimer) {
+        m_killTimer->stop();
+    }
+
     Job *job = static_cast<Job *>(parent());
     // update timestamp
     job->resetUpdated();

libnotificationmanager/jobsmodel_p.cpp

@@ -482,15 +482,10 @@ void JobsModelPrivate::onServiceUnregistered(const QString &serviceName)
         if (job->state() == Notifications::JobStateStopped) {
             continue;
         }
-        job->setError(KIO::ERR_OWNER_DIED);
-        job->setErrorText(i18n("Application closed unexpectedly."));
-        job->setState(Notifications::JobStateStopped);
-
-        // basically JobPrivate::finish()
-        // update timestamp
-        job->resetUpdated();
-        // when it was hidden in history, bring it up again
-        job->setDismissed(false);
+
+        job->d->terminate(KIO::ERR_OWNER_DIED,
+                          i18n("Application closed unexpectedly."),
+                          {} /*hints*/);
     }
 
     Q_ASSERT(!m_serviceWatcher->watchedServices().contains(serviceName));