MAGETWO-35520: Page content jumps when float button bar in Backend appears/disappears

- QA update

Author: Oleg Zinoviev

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/main/_actions-bar.less

@@ -37,7 +37,7 @@
     margin: 0 0 @indent__l;
     &._hidden {
         .store-switcher {
-            &:extend(.abs-no-display all);
+            display: none;
         }
     }
 }