shrink-osd: various fixes

shrink-osd: various fixes

This handles missing /etc/ceph/osd, by ensuring we actually found files in
`/etc/ceph/osd` before trying to slurp their content.

This also add a missing `| default(False)` to avoid fowlloing error:

```
fatal: [ceph01]: FAILED! =>
  msg: |-
    The conditional check 'ceph_osd_data_json[item.2]['encrypted'] | bool' failed. The error was: error while evaluating conditional (ceph_osd_data_json[item.2]['encrypted'] | bool): 'dict object' has no attribute 'encrypted'
```

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1862416
Signed-off-by: Benoît Knecht <bknecht@protonmail.ch>