statusbar: Fix status text still showing when statusbar is hidden

(Maybe we can use `display: none;` here instead? I am not sure how that
would interact with the animation though.)

src/scss/_statusbar.scss

@@ -13,6 +13,7 @@
 }
 
 .uppy-StatusBar[aria-hidden=true] {
+  overflow-y: hidden;
   height: 0;
 }