Reverts syl20bnr#16178

- Recent PR change ":after files" with deferred loading which doesn't seem to
determinably solve the problem with Emacs 29 of restart-emacs/restart-emacs
colliding with files/restart-emacs (introduced with Emacs 29 with fewer args).

- Switch to ":require files" to ensure it's loaded before the restart-emacs
package, so the restart-emacs/restart-emacs function ovewrites the core function
and not the other way around.

- May be REVERTABLE depending on how upstream copes with this change.

See also: syl20bnr#16185

layers/+spacemacs/spacemacs-navigation/packages.el

@@ -356,7 +356,7 @@
 
 (defun spacemacs-navigation/init-restart-emacs ()
   (use-package restart-emacs
-    :defer (spacemacs/defer)
+    :requires files
     :init
     (spacemacs/set-leader-keys
       "qd" 'spacemacs/restart-emacs-debug-init