Cancel outbound operations only in the osd_client_t destructor

This is required to prevent disconnected peers from sometimes receiving messages
suited for other peers - stop_client was freeing the operations even though they
were still references in the io_uring requests in progress. This was leading to
OSDs sometimes receiving garbage and "broken sequencing" errors in logs as the
memory was usually already reallocated for other operations

src/client/messenger.h

@@ -99,6 +99,7 @@ struct osd_client_t
     std::vector<osd_op_t*> zc_free_list;
 
     ~osd_client_t();
+    void cancel_ops();
 };
 
 struct osd_wanted_peer_t