test: load system exact UserGroup by id

Author: jaredhendrickson13

pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Tests/APIModelsUserGroupTestCase.inc

@@ -158,7 +158,7 @@ class APIModelsUserGroupTestCase extends TestCase {
         $this->assert_does_not_throw(
             callable: function () {
                 # Create a UserGroup with the system scope to test with
-                $admin_group = UserGroup::query(name: 'admins')->first();
+                $admin_group = new UserGroup(id: 0);
                 $admin_group->validate_scope('system');
             },
         );