Before this patch, all privacy consent emails were forced to be sent under a context with `mark_consent_sent=True` to track the state change and trigger the attached server action.
When using the automatic mode, if a separate cron job started running the mail queue, it could happen that mails were being sent from that another worker, losing the context key and, as such, being sent without token and without being marked as sent nor executing the attached server action (if any).
To avoid this problem, now the context dependency is removed. After all, the `mail.mail` object is only created when sending in `mass_mail` model, so other kind of notifications or messages are not affected. When a mail of type `mass_mail` is sent, we can assume that it is asking for consent and we can move draft consent requests to sent.
The purpose of this `@post_install` no longer exists, and by removing these decorators, we avoid test failures in case some custom addon customizes the welcome message.