Remove old/unnecessary reboot bug fix (#32631)

From initial testing, this bug doesn't seem to manifest itself anywhere in Bootstrap (since we don't just set transparent background anywhere on buttons, and when we do set explicit button styles in the more specific stylings, we already do create a custom `:focus` style anyway)

Co-authored-by: XhmikosR <xhmikosr@gmail.com>

scss/_reboot.scss

@@ -411,15 +411,6 @@ button {
   border-radius: 0;
 }
 
-// Work around a Firefox 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;
-}
-
 // 1. Remove the margin in Firefox and Safari
 
 input,