neonvm-controller: Don't retry update on conflict (#796)

The previous logic would:

1. Try to update the status
2. If we got a conflict, overwrite the current VirtualMachine object
equal to the state on the API server
3. Then, retry with the udpated object (without changing anything!)

This is basically doing extra work for nothing!

We discussed potentially changing this to overwrite the status on
conflict, but this could result in issues when operating on stale data
(e.g., overwriting .status.podName back to "" after it was already
created).

ref https://www.notion.so/neondatabase/Autoscaling-Team-Internal-Sync-179c7d597dbb4fe5b565d9c482d4d166
ref https://neondb.slack.com/archives/C03TN5G758R/p1707414998235459

neonvm/controllers/virtualmachine_controller.go

@@ -168,32 +168,13 @@ func (r *VirtualMachineReconciler) Reconcile(ctx context.Context, req ctrl.Reque
 		return ctrl.Result{}, err
 	}
 
-	// update status after reconcile loop (try 10 times)
-	statusNow := statusBefore.DeepCopy()
-	statusNew := virtualmachine.Status.DeepCopy()
-	try := 1
-	for try < 10 {
-		if !DeepEqual(statusNow, statusNew) {
-			// update VirtualMachine status
-			// log.Info("DEBUG", "StatusNow", statusNow, "StatusNew", statusNew, "attempt", try)
-			if err := r.Status().Update(ctx, &virtualmachine); err != nil {
-				if apierrors.IsConflict(err) {
-					try++
-					time.Sleep(time.Second)
-					// re-get statusNow from current state
-					statusNow = virtualmachine.Status.DeepCopy()
-					continue
-				}
-				log.Error(err, "Failed to update VirtualMachine status after reconcile loop",
-					"virtualmachine", virtualmachine.Name)
-				return ctrl.Result{}, err
-			}
+	// If the status changed, try to update the object
+	if !DeepEqual(statusBefore, virtualmachine.Status) {
+		if err := r.Status().Update(ctx, &virtualmachine); err != nil {
+			log.Error(err, "Failed to update VirtualMachine status after reconcile loop",
+				"virtualmachine", virtualmachine.Name)
+			return ctrl.Result{}, err
 		}
-		// status updated (before and now are equal)
-		break
-	}
-	if try >= 10 {
-		return ctrl.Result{}, fmt.Errorf("unable update .status for virtualmachine %s in %d attempts", virtualmachine.Name, try)
 	}
 
 	return ctrl.Result{RequeueAfter: time.Second}, nil