Remove transition animation from sort arrows (#6067)

It may be an Ember bug: in some circumstances, the
ember-transitioning-in class was persisting in table
sort links even after the transition completed. This
changes the transition animations to be targeted only
for breadcrumbs and directory links.

ui/app/styles/components/fs-explorer.scss

@@ -18,7 +18,8 @@
     }
   }
 
-  a {
+  .breadcrumb a,
+  tbody a {
     position: relative;
 
     // This is adapted from Bulma’s .button.is-loading::after