config: disable chain backend health checks by default

In this commit, we disable the chain backend health checks by default,
as it seems for bitcoind there might be some lingering false positives.
However, those that wish to opt into the new safety features are still
free to toggle them on.

config.go

@@ -97,7 +97,7 @@ const (
 	defaultChainInterval = time.Minute
 	defaultChainTimeout  = time.Second * 10
 	defaultChainBackoff  = time.Second * 30
-	defaultChainAttempts = 3
+	defaultChainAttempts = 0
 
 	// Set defaults for a health check which ensures that we have space
 	// available on disk. Although this check is off by default so that we