fix: do not delete non-existing dashboard

controllers/dashboard_controller.go

@@ -307,6 +307,9 @@ func (r *GrafanaDashboardReconciler) onDashboardDeleted(ctx context.Context, nam
 				var notFound *dashboards.GetDashboardByUIDNotFound
 				if !errors.As(err, &notFound) {
 					return err
+				} else {
+					// if the dashboard is not found, then we can return directly here
+					return nil
 				}
 			}
 			dash := resp.GetPayload()