Don't add "Seed Resize: -1x-1" to API image metadata

[missionfloyd]

Description

create_infotext() checks if seed_resize_from_h and seed_resize_from_w are 0 while they default to -1, so Seed Resize: -1x-1 gets added to the metadata of images generated with the API unless otherwise specified.

Checklist:

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

[altoiddealer]

I just posted in #11247 that it doesn't seem like the Seed Resize was actually causing issues, after all.

However, it's probably a good idea to just make it default to 0 instead of -1 anyway :)

[missionfloyd]

It would stop it from adding Seed Resize: -1x-1 to the metadata, but so would changing this to <= 0. https://github.com/AUTOMATIC1111/stable-diffusion-webui/blob/394ffa7b0a7fff3ec484bcd084e673a8b301ccc8/modules/processing.py#L576