journalctl: flip to --full by default

journalctl: flip to --full by default

We already shew lines in full when using a pager or not on a
tty. The commit disables ellipsization in the sole remaining case,
namely when --follow is used.

This has been a popular request for a long time, and indeed, full
output seems much more useful. Old behaviour can still be requested by
using --no-full. Old options retain their behaviour for compatiblity,
but aren't advertised as much. This change applies only to jornalctl,
not to systemctl, when ellipsization is useful to keep the layout.

https://bugzilla.redhat.com/show_bug.cgi?id=984758