eth/gasprice: improve stability of estimated price (#22722)

This PR makes the gas price oracle ignore transactions priced at `<=1 wei`.

eth/gasprice/gasprice.go

@@ -199,6 +199,9 @@ func (gpo *Oracle) getBlockPrices(ctx context.Context, signer types.Signer, bloc
 
 	var prices []*big.Int
 	for _, tx := range txs {
+		if tx.GasPriceIntCmp(common.Big1) <= 0 {
+			continue
+		}
 		sender, err := types.Sender(signer, tx)
 		if err == nil && sender != block.Coinbase() {
 			prices = append(prices, tx.GasPrice())