When detaching a device from a domain we first attempt to remove the
device from both the persistent and live configs before looping to
ensure the device has really been detached from the running live config.
Previously when this failed we logged an error message that suggested
that this was due to issues detaching the device from a transient
domain, however this is not the case as the domain is persistent.
This change simply updates the error and associated comments to only
reference the live config of the domain.
Additionally a DEBUG line claiming that a device has been successfully
detached is now only logged once the device is removed from the live
config, hopefully avoiding any confusion from this line been logged
each time an attempt is made to detach the device.