perf: remove getBlock request in feeHistory

[mattsse]

the basefee of the "Latest" block is the second last entry in the vec, if the feeHistory response is correct then we don't need to fetch the block.

this keeps the block request as fallback but perhaps we should just error here?

see MM for ref:

https://github.com/MetaMask/core/blob/main/packages/gas-fee-controller/src/fetchGasEstimatesViaEthFeeHistory/calculateGasFeeEstimatesForPriorityLevels.ts#L62

[mattsse]

the failing test looks more like an anvil issue

 FeeHistory {
    base_fee_per_gas: [
        0x0_U256,
        0x0_U256,
    ],
    gas_used_ratio: [
        0.0,
    ],

hmm looks like returning 0s pre 1559 is expected, so perhaps we should use this as the check?
if base fee is 0 then 1559 is not supported.

although this request would most likely fail because eth_feeHistory does not exist for networks without 1559

so we need to check against the error I suppose

[mattsse]

Update:

basefee entries are 0 pre EIP-1559 for eth_feeHistory

https://github.com/ethereum/go-ethereum/blob/767b00b0b514771a663f3362dd0310fc28d40c25/eth/gasprice/feehistory.go#L83-L83

so this checks for is_zero to fallback to getBlock to confirm, although we could just return an error here because 0 is unreachable anyway