use read only pool - object reclaimer first find

Signed-off-by: Amit Prinz Setter <alphaprinz@gmail.com>

Author: alphaprinz

src/server/object_services/md_store.js

@@ -776,6 +776,7 @@ class MDStore {
         }, {
             limit: Math.min(limit, 1000),
             hint: 'deleted_unreclaimed_index',
+            preferred_pool: 'read_only',
         });
         return results;
     }