remove unneeded hardcoded route name from admin

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

These assignments are no longer needed. If we have them, an admin extending this class must overwrite the fields.

Admin/StaticContentAdmin.php

@@ -20,8 +20,6 @@
 
 class StaticContentAdmin extends Admin
 {
-    protected $baseRouteName = 'cmf_content_staticcontent';
-    protected $baseRoutePattern = '/cmf/content/staticcontent';
     protected $translationDomain = 'CmfContentBundle';
 
     public function getNewInstance()