[10.x] Minor skeleton slimming (#6159)

* remove rate limiter from route provider by default

* remove policy place holder

* remove broadcast skeleton in favor of new provider in core

* use default provider collection

* Remove unnecessary properties from exception handler.

* add back broadcast provider

* update comment

* add rate limiting

* Apply fixes from StyleCI

* fix formatting

---------

Co-authored-by: StyleCI Bot <bot@styleci.io>

app/Http/Kernel.php

@@ -48,7 +48,7 @@ class Kernel extends HttpKernel
     /**
      * The application's middleware aliases.
      *
-     * Aliases may be used to conveniently assign middleware to routes and groups.
+     * Aliases may be used instead of class names to conveniently assign middleware to routes and groups.
      *
      * @var array<string, class-string|string>
      */