ceph-config: always set _osd_memory_target
ceph-config: always set _osd_memory_target

this should be set when rolling_update is true as well, otherwise, it will reset to default on the upgrade

Signed-off-by: Seena Fallah <367913d4df628ad6321bda291c1f2d6ae5e2f066@gmail.com>

ceph/ceph-ansible,ceph/ceph-ansible