Remove old/unnecessary reboot bug fix

Manual backport of #32631

Author: patrickhlauke

scss/_reboot.scss

@@ -307,15 +307,6 @@ button {
   border-radius: 0;
 }
 
-// Work around a Firefox/IE bug where the transparent `button` background
-// results in a loss of the default `button` focus styles.
-//
-// Credit: https://github.com/suitcss/base/
-button:focus {
-  outline: dotted 1px;
-  outline: -webkit-focus-ring-color auto 5px;
-}
-
 input,
 button,
 select,