fetcher does not ensure peer is connected before requesting

[countvonzero]

Description

code https://github.com/spacemeshos/go-spacemesh/blob/develop/fetch/fetch.go#L486-L490

for _, req := range requests {
		p, exists := f.hashToPeers.GetRandom(req.Hash, req.Hint, rng)
		if !exists {
			p = randomPeer(peers)
		}
                ...
}

it gets random peers that registered as hash providers, but it doesn't check if we are connected with that peer.
so for example on my computer i loop with for almost 20 minutes.

2023-08-31T08:41:17.708+0200 WARN fd68b.fetcher failed to fetch blocks {"node_id": "fd68b9397572556c2f329f3e5af2faf23aef85dbbbb7e38447fae2f4ef38899f", "module": "fetcher", "error": "hint: blocksDB, hash: 0xa7fda17e3b073d66aa94e251207faca321e39e7f000000000000000000000000, err: batched request failed w retries: peer is not connected: 12D3KooWCdy5ELnzUoA8kDzG26444DqjSjbNgGMKT3fHPJo7oLmP"}
...
2023-08-31T08:58:01.793+0200 WARN fd68b.fetcher failed to fetch blocks {"node_id": "fd68b9397572556c2f329f3e5af2faf23aef85dbbbb7e38447fae2f4ef38899f", "module": "fetcher", "error": "hint: blocksDB, hash: 0xa7fda17e3b073d66aa94e251207faca321e39e7f000000000000000000000000, err: batched request failed w retries: peer is not connected: 12D3KooWCdy5ELnzUoA8kDzG26444DqjSjbNgGMKT3fHPJo7oLmP"}