This PR tries to improve https://github.com/bnb-chain/bsc/pull/2680 If the node did not set `Eth.Miner` in config.toml, the default GasCeil will be 30000000, it is not an accurate number for both BSC mainnet and testnet. Set it to 0 means disable the transaction GasLimit check, i.e. the TxPool will accept transactions with any GasLimit size.