More detailed "backup failed" email notifications

[tylerdurden4285]

Currently email notifications about failed backups look like this:

Database backup for mariadb (db:wordpress) with frequency of daily was FAILED.

I have multiple WordPress running on mariadb so it can be difficult to find the exact problem website to troubleshoot resolve the issue.

At the very least just add the container name so that the user can be notified of which container has failed it's database backup so they don't have to guess and spend a lot of time finding it.