Checkmk Werk 11614: Fix crash when configuring icon visibility of custom icons

ID: 11614 Title: Fix crash when configuring icon visibility of custom icons Component: Setup Level: 1 Class: Bug fix Version: 2.1.0i1 When configuring the icon visibility using the global setting "Custom icons and actions" of custom icons "Builtin icon visibility" the exception "AttributeError (type object 'CustomIconHttp' has no attribute '_title')" could occur.