heartbeat peers need to be updated when a new OSD added into an existed cluster
The case is:
There is a storage node which has two osds. nearly one min later, a new OSD joins in. Monitor sees it as "up", and no heatbeat from existing two osds to this new one. When we kill this new OSD, no osd reports this to monitor, so monitor still treats it as "up". Then, if the user invokes fio, io may hang there.