Using calldata when not needed

Calldata.md

In StakingTokenProvider, we have two method using calldata for passing string that do not call external contracts. Calldata should be used just when the argument will be used to call an external contract

    function setPairedTokenForVaultToken(
        address _vaultToken,
        address _newPairedToken,
        string calldata _newPrefix
    ) external onlyOwner {
        emit NewPairedTokenForVault(
            _vaultToken,
            pairedToken[_vaultToken],
            _newPairedToken
        );
        pairedToken[_vaultToken] = _newPairedToken;
        pairedPrefix[_vaultToken] = _newPrefix;
    }

    function setDefaultPairedToken(
        address _newDefaultPaired,
        //FIXME: Calldata ??
        string calldata _newDefaultPrefix
    ) external onlyOwner {
        emit NewDefaultPaired(defaultPairedToken, _newDefaultPaired);
        defaultPairedToken = _newDefaultPaired;
        defaultPrefix = _newDefaultPrefix;
    }