Redundant or Error in 'mask' and 'mask_r2' Creation Code

[lynn-1998]

https://github.com/theislab/cpa/blob/0079659badcea71804a6064ea69619e3e7d2d7d0/cpa/_model.py#L394C40-L394C52

the creation of both mask and mask_r2 utilizes the same vectorized function call