Function pause_node 

pub fn pause_node(handle: &RedisServerHandle, duration: Duration)

Freeze a node for a fixed duration, then resume it automatically.

Sends SIGSTOP immediately and returns without blocking. A background tokio task sleeps for duration and then sends SIGCONT, so the node comes back on its own – there’s no need to call resume_node or recover afterward. Useful for testing timeout handling where the outage has a bounded, known length.