Remove `mps` workaround for `isin()`

[pcuenca]

Feature request

Remove mps workaround for isin()

Motivation

#30376 introduced a workaround for isin() on mps devices, because PyTorch does not support that op yet: https://github.com/pytorch/pytorch/issues/77764#issuecomment-2067838075.

Going forward, it'd be desirable to use the much more readable isin() version. This issue is meant to track PyTorch support of isin() on mps so we can remove the workaround and simplify the code.

Your contribution

I can submit a PR when the op is eventually supported.

[amyeroberts]

Thanks for creating an issue @pcuenca so we can track!

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the contributing guidelines are likely to be ignored.

[pcuenca]

Add wip label to exempt from stale bot.