Astro SSR image prerendering test case

Running yarn build in this Astro repo should generate multiple versions of the Stortorget.jpg for the Picture component on the prerendered home page at build time, but it doesn't.

To compare:

• Comment out output and adapter in astro.config.mjs.
• Run yarn build.
• ls -R dist and note that there are several Stortorget.* images.
• Uncomment output and adapter.
• Run yarn build.
• ls -R dist and note that there are is only one Stortorget.* image.

The page does work in yarn preview, because the /_image URL generates images on demand, but it consumes server resources.