test: Fix regression in ownership of /var/lib/cockpit dir

This should be group writable by wheel so wheel users
can add/remove machines.

Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>
Fixes #853
Closes #882
ws: Prevented the unnecessary warning.

Reviewed-by: Patrick Uiterwijk <puiterwijk@redhat.com>
Fixes #858
Closes #883