Refactor PhabricatorBadgesEditRecipientsController to remove dead code

Summary: `$form` in `$dialog = id(new AphrontDialogView())->appendForm($form)` is only defined when `if ($can_edit)` was `true` beforehand. But that was always true. Thus add a variable definition (and remove some unused variables like `$form_box`).

Test Plan:
Visit the page /badges/recipients/1/ or also directly /badges/recipients/1/add/ and add some recipients. It still works as before.

Visit the page without enough permissions. It does not allow to edit them, as before.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25744

src/applications/badges/controller/PhabricatorBadgesEditRecipientsController.php

@@ -49,16 +49,6 @@ final class PhabricatorBadgesEditRecipientsController
         ->setURI($view_uri);
     }
 
-    $can_edit = PhabricatorPolicyFilter::hasCapability(
-      $viewer,
-      $badge,
-      PhabricatorPolicyCapability::CAN_EDIT);
-
-    $form_box = null;
-    $title = pht('Add Recipient');
-    if ($can_edit) {
-      $header_name = pht('Edit Recipients');
-
     $form = new AphrontFormView();
     $form
       ->setUser($viewer)
@@ -68,7 +58,6 @@ final class PhabricatorBadgesEditRecipientsController
           ->setName('phids')
           ->setLabel(pht('Recipients'))
           ->setDatasource(new PhabricatorPeopleDatasource()));
-    }
 
     $dialog = id(new AphrontDialogView())
       ->setUser($viewer)