Checkmk Werk 15169: host_config & folder_config: fix validation for remove_attributes when using custom attributes

ID: 15169 Title: host_config & folder_config: fix validation for remove_attributes when using custom attributes Component: REST API Level: 1 Class: Bug fix Version: 2.2.0i1 Prior to this werk, the REST-API returned a 400 error when a custom attribute was provided in the remove_attributes field in the update endpoint. This werk fixes this error by passing the validation mechanism to the endpoint.