bugfix: skip cache incomplete model weights when initialize

[zcc35357949]

Description

during first webui initialization, sd model are loaded through LoadStateDictOnMeta helper. It will pop state_dict keys, so this incomplete state_dict should not cache to checkpoints_loaded.

fix #13914

Screenshots/videos:

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[AUTOMATIC1111]

if you check the latest dev there's actually a different solution applied (cache a copy before calling load_state_dict)

[zcc35357949]

if you check the latest dev there's actually a different solution applied (cache a copy before calling load_state_dict)

ok, Indeed this solution may be better. Thanks.