stats PR 19498 needs review (Perf: Vectorize Ripley's K "var-width" mode for very significant speedups)

[Pey Lian Lim]

Need someone with expertise in astropy.stats Ripley's K "var-width" mode to review https://github.com/astropy/astropy/pull/19498 that wants to speed up compute time for that mode at the expense of more memory usage. Thanks!