Make sure files in etc are only created on first install and not
overwritten by subsequent updates.
This fixes the problem, that the following files are always
overwritten by updates:
/usr/local/etc/teddycloud/tonieboxes.json
/usr/local/etc/teddycloud/tonies.json
And also the nightly checksum test does not complain anymore.
PR: 287263
Reported by: Matthias Fechner <mfechner@FreeBSD.org>
Tested by: Michael Pape <freebsd@pe82.de>