cmd, core, eth, miner: remove txpool gas price limits (#14442)

cmd/utils/flags.go

@@ -237,7 +237,7 @@ var (
 	GasPriceFlag = BigFlag{
 		Name:  "gasprice",
 		Usage: "Minimal gas price to accept for mining a transactions",
-		Value: big.NewInt(20 * params.Shannon),
+		Value: eth.DefaultConfig.GasPrice,
 	}
 	ExtraDataFlag = cli.StringFlag{
 		Name:  "extradata",