Removed setting override system due to confusing behaviour

- Was only used to disable registration when LDAP was enabled.
- Caused saved option not to show on settings page causing confusion.
- Extended setting logic where used to take ldap into account instead of
global override.
- Added warning on setting page to show registration enable setting is
not used while ldap is active.

For #1541

tests/Auth/Saml2Test.php

@@ -3,7 +3,7 @@
 use BookStack\Auth\Role;
 use BookStack\Auth\User;
 
-class Saml2 extends TestCase
+class Saml2Test extends TestCase
 {
 
     public function setUp(): void

tests/Uploads/UsesImages.php

@@ -15,7 +15,7 @@ trait UsesImages
         if (is_null($fileName)) {
             $fileName = 'test-image.png';
         }
-        
+
         return base_path('tests/test-data/' . $fileName);
     }