This can be helpful when debugging HAOS issues. Dropbear is only started
for users which actually enabled it by configuring a SSH key, so this
change won't have an effect for most people.
So far the exit code has been evaluated, which seems to be non-zero even
with a regular term signal. With that systemd assumed the service is in
a failed state, when in fact this seems the regular behavior of dropbear
when shutting it down.
