pkg/cvo/sync_worker: Grow logging in SyncWorker.Update

To make it easier to debug situations where the CVO's Operator.sync logs

  Desired version from spec is ...

but the sync worker itself doesn't seem to pick up the update [1,2].

[1]: https://bugzilla.redhat.com/show_bug.cgi?id=1843505#c19
[2]: https://bugzilla.redhat.com/show_bug.cgi?id=1873900

pkg/cvo/sync_worker.go

@@ -213,7 +213,13 @@ func (w *SyncWorker) Update(generation int64, desired configv1.Update, overrides
 		w.work.Generation = generation
 	}
 
-	if work.Empty() || equalSyncWork(w.work, work) {
+	if work.Empty() {
+		klog.V(5).Info("Update work has no release image; ignoring requested change")
+		return w.status.DeepCopy()
+	}
+
+	if equalSyncWork(w.work, work) {
+		klog.V(5).Info("Update work is equal to current target; no change required")
 		return w.status.DeepCopy()
 	}
 
@@ -234,12 +240,15 @@ func (w *SyncWorker) Update(generation int64, desired configv1.Update, overrides
 	// notify the sync loop that we changed config
 	w.work = work
 	if w.cancelFn != nil {
+		klog.V(5).Info("Cancel the sync worker's current loop")
 		w.cancelFn()
 		w.cancelFn = nil
 	}
 	select {
 	case w.notify <- struct{}{}:
+		klog.V(5).Info("Notify the sync worker that new work is available")
 	default:
+		klog.V(5).Info("The sync worker has already been notified that new work is available")
 	}
 
 	return w.status.DeepCopy()