MQE-1187: Fix MFTF skipped tests

- LoadingMask addition for test stability.

Author: KevinBKozan

app/code/Magento/Sales/Test/Mftf/ActionGroup/AdminOrderActionGroup.xml

@@ -298,6 +298,7 @@
         <waitForPageLoad stepKey="waitForStoresPageOpened"/>
         <click stepKey="chooseStore" selector="{{AdminOrderStoreScopeTreeSection.storeForOrder(storeView.name)}}"/>
         <scrollToTopOfPage stepKey="scrollToTop"/>
+        <waitForPageLoad stepKey="waitForStoreToAppear"/>
         <click selector="{{OrdersGridSection.addProducts}}" stepKey="clickOnAddProducts"/>
         <waitForPageLoad stepKey="waitForProductsListForOrder"/>
         <click selector="{{AdminOrdersGridSection.productForOrder(product.sku)}}" stepKey="chooseTheProduct"/>