ceph-handler: Fix check mode

ceph-handler: Fix check mode

When running in check mode with one or more Ceph daemons that need to be
restarted, the `tmpdirpath.path` variable that several handlers rely on is
undefined, leading to fatal errors.

This commit ensures the tasks that require `tmpdirpath.path` are skipped when
it's undefined.

Signed-off-by: Benoît Knecht <bknecht@protonmail.ch>