Description of change
From 2.4 we have introduced a slight change in the way that 'create-backup' command was run - backups are now downloaded to the client by default instead of the old way where we stored them remotely by default.
This PR updates help text for the command. But also ensures that the operator is clear whether the backup is available remotely or not.
Whilst running unit tests locally, I have also noticed that we were not removing test-generated files. I have adjusted tests' cleanup.
Documentation changes
/docs I think this has been covered when the original behavior change was done to resolve https://bugs.launchpad.net/juju/+bug/1749300 in https://github.com/juju/juju/pull/8663.
Bug reference
https://bugs.launchpad.net/juju/+bug/1786253
该提问来源于开源项目：juju/juju
