No need to temporarily save old values when updating settings

[code423n4]

Handle

kenzo

Vulnerability details

In updateStreamParams and updateFeeParams, the old values are being saved (probably in order to log them) before being updated.
This is unnecessary.

Impact

Small amount of gas can be saved. (Although maybe it was done this way for code clarity..?)

Proof of Concept

In updateFeeParams
https://github.com/code-423n4/2021-11-streaming/blob/main/Streaming/src/Locke.sol#L850:#L855:

function updateFeeParams(GovernableFeeParams memory newFeeParams) public governed {
        require(newFeeParams.feePercent <= MAX_FEE_PERCENT, "fee");
        GovernableFeeParams memory old = feeParams;
        feeParams = newFeeParams;
        emit FeeParametersUpdated(old, newFeeParams);
    }

The code can be changed to:

function updateFeeParams(GovernableFeeParams memory newFeeParams) public governed {
        require(newFeeParams.feePercent <= MAX_FEE_PERCENT, "fee");
        emit FeeParametersUpdated(feeParams, newFeeParams);
        feeParams = newFeeParams;
}

Same thing can be done in updateStreamParams.
https://github.com/code-423n4/2021-11-streaming/blob/main/Streaming/src/Locke.sol#L841:#L848