rgw: fix segfault in OpsLogRados::log when realm is reloaded

rgw: fix segfault in OpsLogRados::log when realm is reloaded

We weren't previously handling the deallocation of the store when
a realm was reloaded. Now passing a const reference to the pointer.

Fixes: https://tracker.ceph.com/issues/54130
Signed-off-by: Cory Snyder <csnyder@iland.com>
(cherry picked from commit 0713f65355586b2f6ceeb6bbce8763158847e5ed)

Conflicts:
	src/rgw/rgw_log.cc
	src/rgw/rgw_log.h

Cherry-pick notes:
- conflicts due to rename of RGWRados to rgw::sal::Store after Pacific

(cherry picked from commit 44a37dc0023a69da33620dc7b6e112221f7a6a0b)