ceph/flax: 2nd host, first 6+1 disks formatted to bluestore, now backfilling

ceph-scripts: avoid usage of `ceph-volume lvm zap` on `ceph-disk` formatted disks, because they start the osds and then they try to delete them. (i use ceph-disk zap now, it may need improvement because it creates a unusable gpt partition table)

Didn't see any problems with restarting hosts with reformatted disks.
They booted normally and started all processes.