Ties round up when they should round to even, when no second argument to round is supplied.

in pseudo code:

round(NumberDecimal("1234.5", 0) = NumberDecimal("1234") //good
round(NumberDecimal("1234.5") = NumberDecimal("1234") //good
round(1234.5, 0) = 1234 //good
round(1234.5) = 1235 // bad

The problem here is that we are using `std::round` for doubles when no second argument is passed, otherwise we use `Decimal128::quantize`, with round ties to even.