Use systemwide sendername and email as default sender

[jadwigo]

There are global settings to set the senderName and senderEmail in the global Bolt config.yml https://github.com/bolt/bolt/pull/7675 https://github.com/bolt/bolt/pull/7675

We should make the global config values the default sender and reply to for the boltforms notifications if no from_name and from_email etc. are set.