Remove prompt for replying with welcome sticker if the user leaves

When "Prompt members to reply to welcome messages with a sticker" is enabled the reply with a sticker button should be automatically removed if the joined user leaves. It feels very awkward to welcome users who is not even on the server. It can be hard to tell if the user has left because you can reply to them even though they are not on the server. It also removes unnecessary clutter from the chat.