The default log level ("WARN") means borgbackup does not output
anything (and exits with a "0" return code) on success.

We'd like to have some more insight into long-running monthly
backup repo checks and turn up the log level to "INFO" with
this change.

See https://borgbackup.readthedocs.io/en/stable/usage/general.html#common-options .

Fixes #136.

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

That makes working with its output in Grafana easier.
Good documentation can be found at
https://borgbackup.readthedocs.io/en/stable/internals/frontends.html#json-output

We want to have this in our own monitoring

refs privatestorageops#416, PrivateStorageio#115

Fixes #118

This reverts commit c8a13555.

Sadly, Borg says this is not a good idea: https://borgbackup.readthedocs.io/en/stable/faq.html#can-i-backup-from-multiple-servers-into-a-single-repository

Spoiler:  This won't work, Borg does not guarantee consistency with
parallel writers to the same repo as I now found out.

It's not really a key, and not really public, but not secret either.
This way, the tests can run.