Fix: cib/fencing: Set status callback before connecting to cluster

Otherwise, we'd at least miss the initial call to crm_status_callback():

init_cs_connection_once() -> crm_get_peer() -> crm_update_peer_uname()
-> crm_status_callback()

Previously for stonithd, it would not be able to broadcast its uname at
the earliest time, which could potentially introduce other issues.