systemctl: rework daemon_reload() functions

systemctl: rework daemon_reload() functions

Let's split out the inner parts of verb_daemon_reload() as a function
daemon_reload() and then stop using the former outside of the verbs
logic, and instead call the latter whenever we need to reload the daemon
as auxiliary opeation.

This should make our logic more systematic as we don't have to provide
fake or misleading argc/argv to verb_daemon_reload() anymore.