Test worker_steal_count hangs sometimes

[Darksonn]

I tried fixing this in the past with #6327, but it seems like that attempt was not enough to fix it, because it's still happening.

tokio/tokio/tests/rt_metrics.rs

Lines 177 to 213 in 431b7c5

	#[test]
	fn worker_steal_count() {
	// This metric only applies to the multi-threaded runtime.
	//
	// We use a blocking channel to backup one worker thread.
	use std::sync::mpsc::channel;
	let rt = threaded_no_lifo();
	let metrics = rt.metrics();
	rt.block_on(async {
	let (tx, rx) = channel();
	// Move to the runtime.
	tokio::spawn(async move {
	// Spawn the task that sends to the channel
	//
	// Since the lifo slot is disabled, this task is stealable.
	tokio::spawn(async move {
	tx.send(()).unwrap();
	});
	// Blocking receive on the channel.
	rx.recv().unwrap();
	})
	.await
	.unwrap();
	});
	drop(rt);
	let n: u64 = (0..metrics.num_workers())
	.map(|i| metrics.worker_steal_count(i))
	.sum();
	assert_eq!(1, n);
	}

For now, I've ignored the test in #6471, but it should be fixed.