cgls: stop showing cgroup ids and xattrs by default

cgls: stop showing cgroup ids and xattrs by default

Those are rather specialized bits of information, useful mostly for debugging.
I use cgls quite often but never had the need to use either of those…
But they take up a significant amount of screen real estate, esp. when
executed as root:

-.slice
├─user.slice (#1683)
│ → user.invocation_id: 74b0bd1258c5485eb969016384e0d06a
│ → trusted.invocation_id: 74b0bd1258c5485eb969016384e0d06a
│ └─user-1000.slice (#6488)
│   → user.invocation_id: b0261a14fe74490d9a9d5266c52cceb6
│   → trusted.invocation_id: b0261a14fe74490d9a9d5266c52cceb6
│   ├─user@1000.service … (#6590)
│   │ → user.invocation_id: 9e1fb54ad07940d8b92c33c81d169f11
│   │ → user.delegate: 1
│   │ → trusted.invocation_id: 9e1fb54ad07940d8b92c33c81d169f11
│   │ → trusted.delegate: 1
│   │ ├─session.slice (#6874)
...

Let's not show them by default, so we can show more cgroups.

(Also, on a terminal, we already highlight delegate units via underlining and
an ellipsis, so 'user.delegate:1' is redundant.)