filestore-to-bluestore: reuse dedicated journal

filestore-to-bluestore: reuse dedicated journal

If the filestore configuration was using a dedicated journal with either
a partition or a LV/VG then we need to reuse this for bluestore DB.

When filestore is using a raw devices then we shouldn't destroy
everything (data + journal) but only data otherwise the journal
partition won't exist anymore.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1790479
Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>