Store vae.config.scaling_factor to prevent missing attr reference (sdxl advanced dreambooth training script)

[Teriks]

In sdxl advanced dreambooth training script

vae.config.scaling_factor becomes inaccessible after: del vae

when: --cache_latents, and no --validation_prompt

What does this PR do?

Fixes a non-existent attribute reference with a particular argument combination.

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Who can review?

@sayakpaul

[sayakpaul]

Thanks!

[linoytsaban]

LGTM, thanks!

[HuggingFaceDocBuilderDev]

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[github-actions]

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.

[iwr-redmond]

Ping to remove stale

[yiyixuxu]

thanks for the PR! sorry we let it go stale