common/admin_socket: fix leak of new m_getdescs_hook

Signed-off-by: Sage Weil <sage@inktank.com>
debug refs on Connection
osd: do not leak heartbeat con refs on reset

We only mark_down if the con is not being reset, but even when it is we
need to drop our ref.

Signed-off-by: Sage Weil <sage@inktank.com>