zdtm: don't run cgroup04 concurrently with other cgroup tests

It uses --manage-cgroup full and can dump and restore cgroup of other tests.

Reported-by: Mr Jenkins
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/cgroup04.desc

-{'flavor': 'h', 'flags': 'suid', 'opts': '--manage-cgroups=full'}
+{'flavor': 'h', 'flags': 'suid excl', 'opts': '--manage-cgroups=full'}