Delete next cell irrespective of last deletion

Right now when multiple cells gets deleted if any one the cell deletion
fails, the control exits with error msg.
This change stores the errors in a list and let next cells deleted.

Closes #OSPRH-10550

controllers/nova_controller.go

@@ -600,18 +600,26 @@ func (r *NovaReconciler) Reconcile(ctx context.Context, req ctrl.Request) (resul
 		return ctrl.Result{}, err
 	}
 
+	var deleteErrs []error
+
 	for _, cr := range novaCellList.Items {
 		_, ok := instance.Spec.CellTemplates[cr.Spec.CellName]
 		if !ok {
 			err := r.ensureCellDeleted(ctx, h, instance,
 				cr.Spec.CellName, apiTransportURL,
 				secret, apiDB, cellDBs[novav1.Cell0Name].Database.GetDatabaseHostname(), cells[novav1.Cell0Name])
 			if err != nil {
-				return ctrl.Result{}, err
+				deleteErrs = append(deleteErrs, fmt.Errorf("Cell '%s' deletion failed, because: %w", cr.Spec.CellName, err))
+
+			} else {
+				Log.Info("Cell deleted", "cell", cr.Spec.CellName)
+				delete(instance.Status.RegisteredCells, cr.Name)
 			}
-			Log.Info("Cell deleted", "cell", cr.Spec.CellName)
-			delete(instance.Status.RegisteredCells, cr.Name)
 		}
+	}
+
+	if len(deleteErrs) > 0 {
+		return ctrl.Result{}, fmt.Errorf("errors: %v", deleteErrs)
 
 	}