Replace EI with a numerically stable alternative with same maxima globally.

[CompRhys]

Throughout this codebase EI is used in several places. Does it make sense to update these to use a numerically stable version equivalent a la https://arxiv.org/abs/2310.20708? This would break the connections as reference methods for the published work but the expectation would be that this is a 'free' improvement to the quality of the algorithms