Force use of VAE decode (tiled)

### Feature Idea

ROCm for me atleast on RX 7800XT is quite unstable during the VAE decode step. That step seems to ignore the --reserve-vram argument and if the vram hits the roof the GPU will get GPU hang of some unknown reason.

One workaround would be to always use the tiled VAE decode so the vram usage never spikes and causes instability.

Thing is that it would be nice to have a setting to always use tiled VAE decode so I don't need to update all my workflows.

### Existing Solutions

_No response_

### Other

See ROCm issue over here:
https://github.com/ROCm/ROCm/issues/3580