[save_pretrained ] Skip collecting duplicated weight

[wejoncy]

What does this PR do?

Many weight in sub moduoles are collected multiple times. It's useless and time-wasting. Sometimes it even induces some issue when CPU/disk offload is enabled.

Fixes # (issue)

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 write any new necessary tests?

@Rocketknight1 @ArthurZucker

[gante]

Hi @wejoncy 👋

I'm not a reviewer for this PR, but I can foresee a request: please share with us a script with an example where your change results in an upgrade 🤗

[SunMarc]

Sounds reasonable ! It would be nice to have comparison with a model before and after this PR as @gante pointed out