api: ->save_config() doesn't need to create container dir

api: ->save_config() doesn't need to create container dir

If we're saving the config file to somewhere that's *not* the container
dir, we don't need to create the container dir. Let's not do this and
thus not require its parent to exist, which can be confusing, especially in
light of the sparse logging through these functions.

Signed-off-by: Tycho Andersen <tycho@tycho.pizza>