fix(BaseNode/detect_disks): filter out used disks
fix(BaseNode/detect_disks): filter out used disks

If the root disk and data disk are all SSD, we will detect wrong disks.

[centos@artifacts-centos8-jenkins-db-node-6cda6fa1-1 ~]$ ls /dev/nvme*n*
/dev/nvme0n1  /dev/nvme0n1p1  /dev/nvme0n1p2  /dev/nvme1n1

Wrong disk arguments in scylla_setup cmdline:

  --disks /dev/nvme0n1,/dev/nvme0n1,/dev/nvme0n1,/dev/nvme1n1

Signed-off-by: Amos Kong <eb01d8f828a6c9a20be4534e72e049aaf41503df@scylladb.com>

scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-cluster-tests