Definition of B Matrix doesn't match the paper referenced.

[MridulS]

https://github.com/scipp/scippneutron/blob/48ff0f34460c493a07ab36272b855660eaf0c1e7/tests/conversion/tof_conversions_test.py#L563C1-L585C6

[jl-wynen]

The code was based on https://docs.mantidproject.org/v6.1.0/concepts/Lattice.html which claims to use the convention from the paper. Since the paper is behind a paywall, this is what I went with originally. Feel free to change it. But keep in mind that this is test code, it is not in the actual package.