ceph-disk: retry cryptsetup remove

ceph-disk: retry cryptsetup remove

Retry a cryptsetup remove ten times. After the ceph-osd terminates, the
device is released asyncrhonously and an attempt to cryptsetup remove
will may fail because it is considered busy. Although a few attempts are
made before giving up, the number of attempts / the duration of the
attempts cannot be controlled with a cryptsetup option. The workaround
is to increase this by trying a few times.

If cryptsetup remove fails for a reason that is unrelated to timeout,
the error will be repeated a few times. There is no undesirable side
effect. It will not hide a problem.

Signed-off-by: Loic Dachary <loic@dachary.org>