config: convert _osd_memory_target to int
config: convert _osd_memory_target to int

ceph.conf doesn't accept float value.

Typical error seen:
```
$ sudo ceph daemon osd.2 config get osd_memory_target
Can't get admin socket path: unable to get conf option admin_socket for osd.2:
parse error setting 'osd_memory_target' to '7823740108,8' (strict_si_cast:
unit prefix not recognized)
```

This commit ensures the value inserted in ceph.conf will be an integer.

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

fgal/ceph-ansible,ceph/ceph-ansible,ceph/ceph-ansible,fgal/ceph-ansible