fix(models): Apply STE in Dac.from_latents to match the forward pass

[harshaljanjani]

What does this PR do?

The following issue was identified and fixed in this PR:

→ Implemented a fix that applies the straight-through estimator to each latent chunk before out_proj, following the straight-through estimator pattern used in the forward pass (DacResidualVectorQuantizer.from_latents was missing STE before calling out_proj). Also fixes some CI regressions, still not sure which commit caused them, but CI is a tad bit happier again :)
→ Added the repro script to the linked issue.

Fixes #43819.

Before the fix (feel free to cross-check; these errors are reproducible):

After the fix (feel free to cross-check):

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you fix any necessary existing tests?

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: dac