Fixed "Update support address" button showing error on success

no issue

- the API response is now empty so returning the parsed response is null/undefined resulting in `<GhTaskButton>` showing a failure state
- switched to returning an enforced `true` value, if there was an error that's handled by the try/catch

ghost/admin/app/components/modal-portal-settings.js

@@ -390,7 +390,7 @@ export default ModalComponent.extend({
                 }
             });
             // this.toggleProperty('showSupportAddressConfirmation');
-            return response;
+            return true;
         } catch (e) {
             // Failed to send email, retry
             return false;