[ethereum/go-ethereum] Miner info is empty in block (#17454)

@APshenkin The miner field in clique algorithm has a different meaning.
Basically, the miner (coinbase) field is used to indicate a target address for `new signer proposal` or `delete signer proposal`.

For more detail, please take a look at this [proposal](https://github.com/ethereum/EIPs/issues/225)