Fix reboot for placeholder links (#29162)

Backport of #29140

scss/_reboot.scss

@@ -194,13 +194,12 @@ a {
   }
 }
 
-// And undo these styles for placeholder links/named anchors (without href)
-// which have not been made explicitly keyboard-focusable (without tabindex).
+// And undo these styles for placeholder links/named anchors (without href).
 // It would be more straightforward to just use a[href] in previous block, but that
 // causes specificity issues in many other styles that are too complex to fix.
 // See https://github.com/twbs/bootstrap/issues/19402
 
-a:not([href]):not([tabindex]) {
+a:not([href]) {
   color: inherit;
   text-decoration: none;