gossip: don't resolve addresses under lock

[erikgrinaker]

Similarly to #70038, in 21.2 we can end up attempting to resolve a DNS address while holding the gossip mutex:

cockroach/pkg/gossip/client.go

Lines 265 to 268 in 45740de

	if _, err := reply.AlternateAddr.Resolve(); err != nil {
	return errors.Errorf("unable to resolve alternate address %s for n%d: %s",
	reply.AlternateAddr, reply.AlternateNodeID, err)
	}

We don't even use the result of this lookup. We should remove it.

Jira issue: CRDB-23469

[blathers-crl]

cc @cockroachdb/replication

[erikgrinaker]

Resolved by #95426.