Skip subgid check

[jonppe]

Disable setting subuid and subgid by default. Add minor comment about alternatives to include_role.

[ikke-t]

Thanks I like the idea. Nowadays it's rather given that user has the sub{g,u}id set. Where as at the time I wrote the playbooks, it typically wasn't there.

I'd like to ask a slight change. I still believe the check is in place, because if not, things won't work. So Instead of not including the task, please allow it to check it always the files, but just make the update conditional. And fail if the line is missing and update is disabled.

[jonppe]

I changed the implementation as proposed. Also noticed that the check wasn't actually working.