Fix #34316

[SebastianM-C]

The differences between the proposed solution in #34771 (comment) are

• use oneunit instead of one (see one and zero inconsistency PainterQubits/Unitful.jl#291)
• add a check for isinf in order to have a similar behavior with the unitless case. Should this be done more generally with something like the following?

function hypot(x, y)
    #Return Inf if either or both inputs is Inf
    if isinf(x) || isinf(y)
        return promote_type(typeof(x), typeof(y))(Inf)
    end

    hypot(x, y)
end

• remove the hypot definition from Furlongs. I looked at why the tests were passing with the previous definition of hypot and I discovered that the fallback was not actually tested because of the additional method.

[SebastianM-C]

Thanks for the review. I added the suggested changes in the latest commit.