[Chore] Update Stable Diffusion 2.x repositories

[iwr-redmond]

Stability AI have removed the Stable Diffusion 2.x repositories from their Huggingface account. As a result, these checkpoints are now stored in the sd2-community legacy account.

[iwr-redmond]

Hi @Teriks I can probably work on this chore in the coming days. Would you like me to target a PR to the main or version_5.0.0 branch?

I hope your vacation continues to be very enjoyable 😉