Ignore user named "default" in users cc module

[jeka]

The user named "default" has a special meaning of creating a user, defined by a distribution (or image creator in general). As of now, ucd creates an actual user named "default" which is not the desired effect. Since a user named "clear" is created unconditionally on the first run what about ignoring users named "default" in the cloud-init?
I think it doesn't worth checking is it the first entry or not (by the specification), just skip over it.

[ahkok]

Yes, this makes sense.