Image downsize happening in editor content when lazyload is disabled

[abaicus]

Description

It seems that right now, when we disable the Scale images & Lazy load option, changing image sizes in the editor returns the optimized URL to the content, which shouldn't happen - the sizes get filtered by the image_downsize filter here.

I think it would be enough to add the following condition at the top of the method the filter uses:

if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
	return $image;
}

@Codeinwp/optimole Let me know if you see any issues with this approach.

Step-by-step reproduction instructions

1. Disable the Scale images & Lazy load;
2. Insert an image in the editor (its URL is the original one - as it should be);
3. Change the image size in the editor sidebar;
4. The image URL will be the optimized one, saving it to the content, which shouldn't happen;
5. You can check the URLs by switching to the code editor in Gutenberg or simply inspecting the editor contents;

Screenshots, screen recording, code snippet or Help Scout ticket

Environment info

No response

Is the issue you are reporting a regression

No