who_am_i may not always return the FQDN

https://github.com/apache/infrastructure-loggy/blob/5d4029a967992615d823ed4a6841ce6fb6832202/loggy.py#L82

has some issues:

- it assumes that socket.gethostname() returns the short hostname, however that is not guaranteed, it may return the FQDN
- if local_hostname does not match the start of any of the canonical names, it picks the first, which may not be the best
- it does not check that the result is a possible FQDN

If local_hostname looks like a FQDN it should probably return that without comparing against the canonical names (which it probably won't match anyway).