MC-32423: Backend - Braintree payments validation overlay issue

Author: tsviklinskyi

app/code/Magento/Braintree/view/adminhtml/web/js/braintree.js

@@ -309,6 +309,7 @@ define([
 
             self.hostedFieldsInstance.tokenize(function (err, payload) {
                 if (err) {
+                    $('body').trigger('processStop');
                     self.error($t('Some payment input fields are invalid.'));
 
                     return false;