[needs QA] fix client side validation - edit group descreption

**CR** : :white_check_mark:

**QA** : :question:

we've fixed client side validation. problem was right-click to paste not triggering character counter update.

**NOTE:** server-side there is a validation, but the *edit_description* action in `group_controller` doesn't catch a failed save. this fix doesn't address that, but makes it very unlikely that a user could reach that point