chaincfg: update dnsseeds (#2174)

* chaincfg: remove unresponsive dnsseed on testnet

testnet-seed.bitcoin.schildbach.de is unresponsive and doesn't return
any ips.  Bitcoin Core has already removed it and we don't also be
getting rid of it as well.

* chaincfg: add dnsseeds from Sjors Provoost

His seeds work well and we don't have any for signet and it's good to
replace the lost dns seed on testnet.

* chaincfg: remove bad dnsseed (seed.bitcoinstats.com)

seed.bitcoinstats.com doesn't respect filter requests even though it's
advertised as it does. Plus it often returns nodes that are unreachable.
In my testing over the past week, it's been the most unreliable dns seed
and since we have plenty of mainnet seeds, it's better to do away with
this.

I documented my findings for this in a Bitcoin Core issue:
bitcoin/bitcoin#29911

* chaincfg: add dnsseed from wiz

It's the same infrastructure that mempool . space runs on and has been
reliable.  The same seed is also included in Bitcoin Core as well.

chaincfg/params.go

@@ -59,6 +59,7 @@ var (
 	// DefaultSignetDNSSeeds is the list of seed nodes for the default
 	// (public, Taproot enabled) signet network.
 	DefaultSignetDNSSeeds = []DNSSeed{
+		{"seed.signet.bitcoin.sprovoost.nl", true},
 		{"178.128.221.177", false},
 		{"2a01:7c8:d005:390::5", false},
 		{"v7ajjeirttkbnt32wpy3c6w3emwnfr3fkla7hpxcfokr3ysd3kqtzmqd.onion:38333", false},
@@ -284,10 +285,11 @@ var MainNetParams = Params{
 		{"seed.bitcoin.sipa.be", true},
 		{"dnsseed.bluematt.me", true},
 		{"dnsseed.bitcoin.dashjr.org", false},
-		{"seed.bitcoinstats.com", true},
 		{"seed.bitnodes.io", false},
 		{"seed.bitcoin.jonasschnelli.ch", true},
 		{"seed.btc.petertodd.net", true},
+		{"seed.bitcoin.sprovoost.nl", true},
+		{"seed.bitcoin.wiz.biz", true},
 	},
 
 	// Chain parameters
@@ -544,8 +546,8 @@ var TestNet3Params = Params{
 	DefaultPort: "18333",
 	DNSSeeds: []DNSSeed{
 		{"testnet-seed.bitcoin.jonasschnelli.ch", true},
-		{"testnet-seed.bitcoin.schildbach.de", false},
 		{"seed.tbtc.petertodd.net", true},
+		{"seed.testnet.bitcoin.sprovoost.nl", true},
 		{"testnet-seed.bluematt.me", false},
 	},