miner: lower default min miner tip from 1 gwei to 0.001 gwei (ethereum#29895)

Author: karalabe

miner/miner.go

@@ -53,7 +53,7 @@ type Config struct {
 // DefaultConfig contains default settings for miner.
 var DefaultConfig = Config{
 	GasCeil:  30_000_000,
-	GasPrice: big.NewInt(params.GWei),
+	GasPrice: big.NewInt(params.GWei / 1000),
 
 	// The default recommit time is chosen as two seconds since
 	// consensus-layer usually will wait a half slot of time(6s)