chainregistry: increase zmq connection timeout with bitcoind backend

There seems to be a misinterpretation of a variable between the
btcwallet and gozmq libraries. When establish a ZMQ connection, it
expects a timeout, which is used to set read deadlines and determine how
long we should wait before attempting a reconnection. Within btcwallet
and lnd however, this is is interpreted as a polling duration,
explaining the current value of 100ms. Under load, especially on
less-capable hardware, this leads to high resource usage as we get into
a constant reconnection loop. To remedy this, we use a timeout of 5s
instead, which is a much more reasonable value for read timeouts, and is
also what's used for LN peers.

chainregistry.go

@@ -314,7 +314,7 @@ func newChainControlFromConfig(cfg *config, chanDB *channeldb.DB,
 			activeNetParams.Params, bitcoindHost,
 			bitcoindMode.RPCUser, bitcoindMode.RPCPass,
 			bitcoindMode.ZMQPubRawBlock, bitcoindMode.ZMQPubRawTx,
-			100*time.Millisecond,
+			5*time.Second,
 		)
 		if err != nil {
 			return nil, err