A financial services company is deploying a FortiGate HA cluster in active-passive mode between two data centers using a stretched VLAN for the HA heartbeat. During a network event, administrators observe that both FortiGates temporarily become master, creating a split-brain scenario. Which FortiOS HA setting is specifically designed to mitigate this condition by allowing a master to shut down monitored interfaces on the secondary unit if it fails to receive heartbeats?