button.js: Fix keyboard navigation

This PR fixes the keyboard navigation again while still keeping #16223 fixed.

Closes #19192

js/tests/visual/button.html

@@ -22,6 +22,8 @@
     <h1>Button <small>Bootstrap Visual Test</small></h1>
   </div>
 
+  <p>Try interacting via mouse, via keyboard, and via keyboard after first interacting via mouse. (Refresh the page between each trial.)</p>
+
   <button type="button" data-loading-text="Loading for 3 seconds..." class="btn btn-primary js-loading-button">
     Loading state
   </button>