cephadm: call container daemon form prepare_data_dir

cephadm: call container daemon form prepare_data_dir

Instead of always climbing through an "if ladder" based on daemon type
variables we will have the option of using the common method provided
by container daemon form classes. This will initially be used by the
smb daemon. I don't have the energy to refactor all the existing stuff
at the moment.

Signed-off-by: John Mulligan <jmulligan@redhat.com>
(cherry picked from commit 0f6a18a09cba35515e100f457e224537ad1e5608)
(cherry picked from commit bf7e40b4d1fee439a4a7f48cf033d4a0885890d0)