Prevent accidental group deletion if path rename fails

If an update to the group path fails validation, the unsaved attributes would still be presented because the controller would fall through and call render on the unsaved group object. There was an attempt to reset the path to the previous value, but this did not work because the Rails form helper called Group#to_param, which loads the full route.

While it may have been intentional to retain the failed values, it's better to be safe and reset all the values back to their original state.

Relates to #241110 (closed)